I am posting herewith notes we made while replacing an 850 evaporator last year. It is an inline post as I did not see a method for attaching a file. We have tried to be reasonably complete. Our A/C still works fine but there are of course no guarantees. Individual cars even of same model may differ. Good luck!

ksg

6-5-06 Procedure and notes for evaporator replacement – Volvo 850:

This procedure applies to a 1995 850 NA with manual climate control. It is derived from many sources including:
Scott, E and JH Haynes, Volvo 850 automotive repair manual (93-97), Somerset (UK): Haynes publishing group (1999).
Notes from “tech” – see www.volvo-forums.com
photo archives – posted on.the web – might find link on www.volvoforums.com
Althouse JV and Rabitt M, Auto air conditioning technology, South Holland (IL, USA): Goodheart-Willcox, 1991.
Notes and posts on Bay13 (www.volvospeed.com)
Notes and posts on www.brickboard.com
Thoughtful friends.

It is helpful to have a general reference book on air conditioner operation, service, and maintenance.

The steps should be done in the listed order unless specifically noted. It is very helpful to have 2 people on this project. Read through the entire procedure so you will know what you are getting into. Have some plastic bags or containers and a marking pen and/or tape so you can organize and label parts you remove and make notes. About ½ day would be needed to review and plan, and a couple of days or so to do the work, probably including runs for supplies.

parts and tools needed:
replacement evaporator
replacement accumulator
pollen filter and its holder (if not already present in your car)
Torx bits: T-15 (a long one is needed to remove steering column covers), 20, 25, 30, a long T-30 bit (to remove steering wheel air bag),18mm socket with extension and ratchet (for steering wheel hub), wire cutters for cable ties,
10mm ,12mm, and 13mm,1/4 drive socket.
Allen wrench 6 mm to remove a/c line retaining clamp
flat and phillips screwdrivers and other common tools.
2 hose clamps to clamp heater hoses (unless you want to drain all the coolant from block and radiator).
spring clip removers for a/c hoses – sizes ½ and 5/8 inch at least – These are Ford-compatible.
vacuum pump and gauge set for recharging – available as a rental in some areas
various O-rings for the a/c lines. We found that only the rings from Volvo fit exactly.
clips, O-rings and spacers for the quick-disconnect heater lines.
Light bulbs for any in panel that are burned out.
any parts found broken or cracked
replacement dash speakers if yours have dried out or cracked.
weatherstrip or sealing tape to seal evaporator into housing
some kind of mandrel or other expedient to bend/align evaporator inlet/outlet tubes.

Find a place to work where you will not need to move the car under power. Park it and set the parking brake, then move the gear lever out of park, for instance to low or 2 (manual to 2nd or 4th so it is away from the dash). You will not be able to remove the ignition key after this, so if you are going to leave the car in an unsecure area, you will need a second key. Later you will be able to remove the ignition lock cylinder with the key if necessary.

Also move the power seats backward to give room to work. You won’t be able to after battery is disconnected.

It will probably be easier to replace the evaporator once you have the climate unit out if you set the recirculation damper to open (non-recirculating) position before starting. You will not be able to move it later until you are done.

Disconnect the battery negative lead. This is essential with respect to the airbags. You should not reconnect the battery lead once you get to the point where you are going to disconnect the airbags, until everything is done. If battery power is reapplied while airbags are not connected fault codes will be triggered. Also do not disturb or disconnect any airbag wiring other than where indicated. There is a possibility of triggering the airbag if sensor or standby power connectors are disturbed. The local connector at each air bag has a shorting plug to ensure it will not go off due to static discharges, etc. Also: Never test an airbag circuit with an ohmmeter or other source of power of any kind. See detail below on how to reconnect power when done. Finally do not have anyone or anything in the line of fire when working on the airbags. These airbag precautions are from Volvo literature. Most of the airbag wiring I found was wrapped with orange tape. Also be aware that the side air bags if equipped are mechanical, not electrical.

Unless all the refrigerant has already leaked out, bleed it out – recover it as required by law in your jurisdiction and if a recovery system is available.

The following steps are done under the hood –

Remove the splash guard under the radiator – this will give some access to the accumulator, condenser, hoses and compressor for inspection. Establish the condition of each of these and how they are fitted in case they will need to be removed. Every source I am aware of says to replace the accumulator along with the evaporator.

Spray the mounting attachments for the accumulator and other fittings with a rust penetrant like “Liquid Wrench” or whatever you have found works well.

Remove the wiper arms.There is a 13mm nut per arm. You may need to remove a black cover to get to the nut.

Then remove the 4 Torx 25 screws holding the plastic cover under the the wiper arms. You will have to also remove the 2 clamps holding the rubber hoses to the plastic cover. Lift up on the front of the cover then slide it towards the front of the car to remove it.

Loosen the 4 Torx 30 or 10mm screws that hold the dash to the body of the car. You could remove them now or leave them in place to secure the dash from slipping around while working inside. This is illustrated in the Haynes book, fig 29.16. Be very careful removing and tightening the screws for the dash.The dash tabs could break and then will need to be repaired or the dash will need to be replaced.

Remove the pollen filter if present and its holder or ring by pulling up

You will need to remove the heater hoses from the heater core. This is necessary so you can move the climate control unit far enough away from the firewall to open the top and get the evaporator out. You can do it before or after removing the dashboard. Clamp the heater hoses tightly (or else drain all of the coolant from both block and radiator and recover it). Remove the 2 heater core lines that go into the firewall. Push the plastic clips on both sides of the hose in then pull on the hose to remove. Keep track of the order and position of the o-rings and gently use a pick or similar to pull them out if retained in the heater core. Prepare to replace the clips and rings unless they are fresh. I don’t have the illustration that came with the hoses. The order I found was (from hose body to tip that goes into heater core) – clip, 1st O-ring, spacer, 2nd O-ring.

Then remove the 2 Torx 15 or 20 screws going through the metal cover on the heater core where you just removed the 2 hoses from, along with the cover and the rubber gasket. You may lose some coolant out of heater core and may want to plug the hoses or heater core.

Next free the A/C lines from their mounting. With a 6 mm Allen wrench you can remove the screw that holds the metal line to the body of the car behind the headlight on the right side of the car. This will help the lines to slide forward when removed from the evaporator. The screw may be badly corroded.

To remove the lines from the evaporator the Ford-style plastic snap-on connector tools are used. The evaporator lines are ½” (inlet) and 5/8” (outlet). The lines should be plugged so moisture is less likely to enter. These lines are sealed with 2 0-rings each. A flare on the evaporator side of each line is held in with a “garter” or circumferential spring which the tool expands. The lines will probably not be easy to separate. I was successful with steady force. Needed tools are made by KD and Snap-On as well as others.

There is a cover plate and gasket to be removed (comparable to heater core).

The following steps are done inside the car – to remove dashboard for access to the entire climate control system.

Remove the center console. You will not be able to access screws securing the dash unless you do. This is fully detailed in the Haynes manual, section 11-28. The following is a similar description from “tech”: On the 850 remove the front cubby by removing the 2 T-25 screws. Under the cover are 2 T-15 screws - remove them. Unplug the black and grey plugs in the hole by the 2 T-15 screws. Then lift up the armrest, remove the black cover and remove the 2 8mm or 10mm screws.The early 850's may have T-25 screws.

Unplug the 2 plugs behind the cover for the parking brake. Lift the back of the center console up first and work it out.

In the console clean the window and mirror switches and check/replace if needed the illuminator bulbs, especially the gear position indicator.

Next remove the radio by pushing in the little tabs on the sides of the radio. They will pop out. Then pull them to release the tabs all the way. Remove and unplug the radio.

This comment is from “tech”: The next step will depend whether you have ECC (Electronic climate control)or MCC(manual climate control). If you have ecc then you can reach through the hole for the radio and push the climate control module from the back. Be careful - put a rag on your arm. Sometimes it is stubborn and when it releases it will cut your arm.

As shown in Haynes, section 3-10, if you have MCC then remove all 3 of the control knobs. Under the 2 outer knobs are 2 T-25 screws. Remove them then push the outside cover out from the back and unplug the wiring. On each side of the control panel you will see one Phillips screw - remove these. From the Haynes book it appears you need to disconnect the control cables from the control panel. We did not need to do this in order to get the dashboard out. However once the dash is out it would be a good time to check the cables etc as to whether they are clean and operate freely. It may be necessary to disconnect the cables to get the climate unit out when it is time to actually replace the evaporator. This depends on whether the cables run under the existing wiring harnesses which you will not remove. Keep some kind of notes as to how the cables run.

Following steps are done to remove the steering wheel. This is detailed in Haynes, section 10-15.

Remove the air bag from the steering wheel. Release the ignition lock to position 1. Turn the steering wheel so that the top is to one side. There is a hole in the back of the steering wheel on each side. Insert a long T-30 and remove the screws for the airbag. Always remove and tighten the right side screw for the air bag first. If not then the horn might not work. You remove the screws then pull the air bag out just enough to disconnect the cable from it (the gold pin connector right at the bag). This connector just pulls straight back. Set air bag aside in a safe place.

Next turn the steering wheel to straight-ahead position. Mark the steering wheel and the splined hub so that you can reinstall the wheel on the same exact teeth as originally used. Otherwise the steering wheel will not be straight when the road wheels are aimed straight and you will need to reinstall it at the end. Break loose the 18 mm steering wheel bolt (without removing it). Take the little T-20 screw stored in the steering wheel. You will then screw it into the hole on top of where the bolt for the steering wheel is. This screw is a keeper to hold the contact reel from unrolling when you pull the steering wheel off. There is a procedure for recentering the contact reel but I don’t see as that would be needed if the retainer is put in the right position at this point.

Remove the bolt holding the steering wheel in. Then lift the steering wheel off.

Next remove the steering column covers. Loosen and remove the T-25 screws in the bottom cover. The screws go in from the bottom going up. These covers are pretty breakable.

On the 850 you will have to remove 2 T-15 screws in the front part of the cover. You will need a long bit to reach the screws. Hold down on the top cover while removing then or the tabs might break off the top cover. The top cover will lift right off, but the bottom will have to be worked off around the tilt adjuster and ignition key.

Next remove the turn signal switch and the wiper switch. They are held on by 2 T-25 screws each. Disconnect these. You can leave them attached or store them away.

Next remove the SRS contact reel. Note: Be very careful - the plastic is very brittle. There are 3 screws total holding it in, which enter from the front. The orientation of the reel has the keeper screw at about 1 o’clock position. Then unplug it and remove it all the way. The plug for the contact reel is just under the column and was orange.

Next remove the lower dash kick panel on the left side of the car if not done already.

Then look up under the dash and you should see a long red plug. We could not see how to remove this plug until we looked at it closely after removing the top dash cover (below) as well as the knee bolster and the instrument cluster (done according to Haynes). The plug has a paired hinge or hook at one end and a retaining tab at the other. When you spread the tab away from the body of the plug it will swing out on the hinge far enough so that it can be separated. The red plug is the main plug for the dash, but we found a secondary black one. The large white plug we also found was not relevant to removing the dash.

While exploring around the connections we also chose to remove the instrument cluster. On Bay13 it says you can lift the top of the dash partially from the left edge to get this out. We did not succeed in getting the cluster out until we had the entire top of the dash off.

Next on the 850 you will have to remove the metal knee bolsters. There is a left and a right bolster which are held in by 13mm nuts. You can wait till you remove the dash. It is easier to remove them once the dash is out. We did the left one first because otherwise we could not see how to get the instrument cluster connectors free (above). The bolsters as fitted go on 4 studs (3 with nuts) very tightly. They are also sharp-edged and can cut your fingers badly. We did something which is probably not approved – we enlarged the holes in the bolsters some with a round file so they could go on and off easier if they ever needed to be removed again. They may have been fitted tight for ease of assembly (so they would not fall down from the mounting studs) or the tight fit may be a part of their safety function.

At the left and right side by the doors are 2 vents that need to come off. The vents are retained by small screws under a cover that needs to be pried off. The screws under them are to be removed. After these are off you will see on each side one of the retaining screws that holds the dash.

We removed all 6 air vents. I think if the entire dash is to come out at once this might not be needed but we took the top off first. Tip each vent downward and pull or pry gently with a screwdriver. At the far left and right are air ducts that will separate. To remove the top of the dash it is necessary to remove the upward directed screws from the air vents as well as 2 from above the instrument cluster, one in the passenger side speaker well (below), and the 2 just mentioned above at the extreme left and right.

The speaker grilles need to be lifted off. We found a retaining screw behind the the passenger side grille. You need to remove and disconnect the speakers (by pushing in the center of the 2 plastic rivets and by removing the connector. If taking the entire dash as one piece this may or may not be needed.

It is now necessary to disconnect the passenger air bag. This should be connected with an orange wrapped wire with a plug. The bag will come out intact I think with the dash if you are taking the entire dash. When taking off the top we needed to remove the 4 10 mm screws holding it along its bottom edge. IMPORTANT – there is a rear central 2 pin connector (with gold pins) to the air bag. You need to first find this and pull it out to avoid straining it when removing the top dash. The Haynes manual did not mention removing the air bag screws in their description of removing the top part of the dash, nor the connector behind the air bag. The air bag came along with the top. This may or may not be an issue when removing the entire dash intact.

The lower right kick panel should be removed if not done yet. Next is the glove box assembly. This is removed as detailed in Bay13 “Passenger dash access.” The glovebox door will stay with the dashboard if you remove the support arms (pry out each arm at the little slits at the door end by inserting a small screwdriver to spring back the retaining tab). The arms will fall back but you will be able to catch them. Remove all the T-25 screws holding it the glovebox in.

There are 6 screws that hold the dash in at the interior. 2 are below and described as follows: - pull back (outward) the sill cover at the bottom of the dash by the door. This is the sill cover that runs all the way back along the door. Remove the screw at each side.

There are 2 other screws at the extreme ends of the dash, which would have been removed for removing the top of the dash.

There also 2 screws which are astride where the console was which stabilize the dash and need to be removed.

The radio and manual climate control panel should by now have been removed already.

You will need to have the key out of the ignition and get the car out of park, otherwise there will not be clearance to remove the dash. If the car is still in park for some reason, look on the right side of the shifter. There is a solenoid. You will need to push the solenoid back and push the button on the shifter to pull it out of park. Chock wheels of car and/or set brake.

If the ignition key is still in, you will need to remove it. Follow the procedure on Bay13 to remove the electrical contactor of the ignition switch. Then follow the procedure in the Haynes manual to remove the lock cylinder with a small drift. There is a hole above the cylinder which allows you to insert the drift and remove the cylinder by wiggling it out, including the key.

The dash should be ready to come out. Make sure you have someone help you remove it – otherwise it will flex lots and may crack. Remove the dash. If your car is a turbo and has a boost gauge you will also have to unplug the line for the boost gauge. Also, be careful - some cars have an extra plug you will have to unplug while removing the dash. Watch while removing. You may have extra wiring to remove if you have any aftermarket stereo, GPS, etc. installed.

Set the dash off to the side in a safe place. Once the dash is out of the way then remove the knee bolsters if you chose to leave them till the dash was out.

Following steps are toward removing the evaporator itself.

Then remove the wiring for the blower motor, resistor pack, and any relays, etc. that are wired in. Also unlock the plastic guide holding the wiring to the fan case, and free the connectors which attach to the fan housing brackets.

Cut the wire ties where the wires are attached to and go across the front of the case. Let them hang for now.

Disconnect the recirculation damper motor. Later you will need to dismount the motor and probably to disconnect the control rod too.

Unplug the connector for the heater control lighting, from the control panel. To do this you will have to remove the black back cover which is held by 3 screws and 2 clips. Removing this cover also allows you to access the heat/airflow control cable ends. These will have to be removed if the cables run under any of the installed wiring.

The following is from “tech”. On the 98 S70 and the 850 look over by the gas pedal and you will see a diaphram and a rod for the cruise contol. Undo the rod from the gas pedal. Then remove the 4 12mm bolts holding the case to the body of the car. Lift up on the case a little then pull it towards you. Note: On the 99 and 2000 S70 you will have to remove the gas pedal and the pedal mount from the body of the car. That will allow room for the heater core lines to pull back from the firewall.

I found the cruise vacuum lung was held on by one screw to the heater housing.

Now remove the carpet backing boards to left and right of the console. There is one screw holding each near the rear and a tab near the front. After removing the screw just slide the board to the rear.

You need to remove the duct to the rear floor. This is kind of tight. We managed to slide the floor ducts back and get a little room to wiggle this out. FIrst though we had to remove the cross bracket attached to the climate unit by 4 screws that runs between the 2 knee bolster supports. We also loosened these 2 supports from their attachments near the rear of the console in the floor and swung them back.

Pull the climate control drain hose out of the floor (leave it attached to the climate unit at the other end).

There are 4 12 mm bolts that hold the climate unit in. Remove them when you are sure everything else is free. Two locating pins are provided on the climate unit, which keep the climate unit from just falling down when you remove the screws.

We found it easier to remove the fan motor and housing so that the passenger (right) end of the climate unit could be freed. The fan motor is held by 4 screws and you can pass it out by rotating the mounting plate to clear the right knee bolster bracket (far right on passenger side).

You might want to remove the rightmost knee bolster support bracket too.

Inside the heater core there will be some coolant and inside the evaporator there may be some oil, dye, etc. There may also be some water inside the climate unit, particularly if the drain was blocked or shortly after a rain. You might want to arrange to catch these things.

Once you have the climate unit loose you can remove it entirely from the car. This was a little difficult due to the gas pedal fouling on the heater lines but we shifted the climate unit a little to the right as we worked and it came out ok. We took it out entirely so that we could check the operation of all the flaps and cables (manual climate control) and scrub out the interior – this may retard mildew etc. from forming later. We lightly relubricated the heater and air flow controls (NOT the cables).

To get to the evaporator you will need to remove the recirc door motor located on the top of the box. Remove it by removing the 3 T-15 screws.

Then remove the rest of the T-15 screws around the evaporator cover. There are several screws and clips. Part of the evaporator cover fits under the air distribution box so the top of this will need to be loosened too.

Once all the screws and clips are out you can remove the upper part of the cover over the evaporator.

Remove the evaporator – observe whether the new inlet and outlet tubes point at the same angles as on the original. These are of hard but bendable aluminum and can be bent with a suitable mandrel or rod – it should be necessary to move the tubes only a few degrees. Only precaution is to avoid distorting the expanded portion and/or the flares at the ends.

Replace the evaporator. Make sure you transfer the rubber seal from the pipes to the new one. The evaporator will have been sealed partly in place with adhesive strips. When installing the new evaporator renew the sealing around its edges. Notice that there are water channels under the evaporator – may be better not to seal the bottom face. Install the climate control top cover and tighten – reinstall the recirc motor. When you stick the box back in make sure the heater core connection and the A/C drain are back where they belong. If the drain is not connected it will leak water into the car and flood the floor board.

ALSO leave the plastic cover on the evap pipes while installing the box back in where it belongs. Also spray some lube on the rubber grommet where the pipes go through. It will make it easier to go in.

Put everything back together in reverse order.

Once everything else in the car is together then if you decide replace the dryer. Then connect all the pipes and put the system on high vaccum for about 1HR. For this purpose I rented a 2-stage vacuum pump. This may be hard to find in some areas and you may need to resort to having a shop evacuate and fill your system.

Then charge the system. You will need normally 26 oz of R134A and also a few oz of PAG oil. I used medium weight, not knowing whether medium or light was used. Heavy weight is specified mostly for GM cars, to my knowledge, not other manufacturers. I added 5 oz of oil, guessing from what I could get to spill out of the old evaporator and accumulator.

Special issue of reconnecting and re-enabling air bags – the 960 literature and the Haynes book both have you FIRST turn on the ignition to 2nd position (not just accessory but igniton and main primary power on), and THEN reconnect the battery. In at least one place it says the SRS warning light should go out after 10 sec if everything is okay. Double check before reapplying power that all the air bag connectors are in place and firm – else there will be a fault code triggered.