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Hi Everyone!
ONGOING ISSUE WITH AC: I replaced my AC cycling (low pressure) switch, but the clutch did not engage on the compressor. However, when the wire plug that connects to that switch was "jumped," the clutch engaged and the AC "pipe" was cold (which is why the switch was suspect).
Any thoughts on what needs to be checked next? There is adequate freon in the system. The shop I go to ordered me the Santech MT0210 Clutch Cycling Switch, which fits my car. Just a tiny bit of freon was released when I took off the old one.
Hoping for some insight!
Thanks much,
Susan
York, PA
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Hi Susan,
I did mention faulty Santech pressostat during my post in your previous thread.
Items like pressostat don't get replaced often. They typically last 10 to 15 years. You're lucky if you could get quality ones over your local counter. These days ordering online is the norm for such item. Quality ones could be ordered via eBay and FCPEuro. Choose dependable manufacturer such as 4-seasons and Behr. Original quality ones could be ordered from Volvo websites such as Volvopartswebstore and Skandix.
Even as a small item it plays an important role as it has to bear all that high pressure (and still not leaking) in a fully charged system - typically around 70 - 80 psi in cold climate and over 100 psi in hot humid climate.
One of the reasons your new pressostat may not function is INADEQUATE system pressure. Shorting those two terminals in that electrical connector showed you have good functioning compressor and AC control board. Have someone read the pressure of your AC system. If pressure is good then your new pressostat is defective. If pressure is low then you need to charge the system to make it work.
Regards,
Amarin.
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Thanks for your input, Amarin! I ended up with the new Santech switch from the shop I go to because I couldn't find one other than "Global" anywhere else. I checked all the sites you listed. I found a Behr switch, yet it didn't fit a wagon, just a 1993 940 sedan. How I wish I could have easily found a new Pressostat!It's considered obsolete at Volvo.
I'm taking it to a shop to get it checked on Thursday. Since the one AC pipe near the accumulator got cold when I was jumping the switch, I figured that the freon should be adequate. Maybe that's not so?
I will be sure to let you all know what's going on. And it's been REALLY hot in Pennsylvania (and humid), so maybe that's factoring in as well.
Thanks again!
Susan
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You could, for the time being, keep jumping the electrical connector and powering the AC via the AC on/off switch at the AC control. But in doing so negates the safety purpose of the pressostat which is to stop all AC when freon is low (this assuming your new pressostat is ok). Yes I could only imagine your heat situation at PA.
Low circulating freon could still slowly cool down the car but we're talking about compressor lubrication here. AC compressor oil normally flows only with adequate freon. Continued AC use in this ambiguous situation may damage your compressor and incur further cost.
I must ask you to refrain AC use till you get to the shop and do pressure readings.
Regd the pressostat, it is still the same item used whether in sedan or wagon. Only in wagon the AC may work a bit longer to cool down the extra air space and heat from extra windows.
Regards,
Amarin.
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Much appreciation, Amarin! I will get the pressure checked on Thursday, along with a good bit of other stuff. It will be so nice to have working AC, as I haven't had it since I've owned the car (about 3 years or so). I've never been able to jump it to keep the AC on, so all's good there.
And with all the heat and humidity here, I just noticed mold growth on the vents in my room air conditioner, which I guess is why I've been having throat and breathing problems. One thing after another. E-gads! NEXT!!!
Wishing you a nice day,
Susan
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Dear smfree,
Hope you're well. Household bleach (usually 6% sodium hypochlorite) if diluted with an equal volume of water, makes a top notch mold and virus killer. Put this mixture in a clean spray bottle.
You might want to take your room airconditioner outside, spray the coils/vents with a bleach/water solution, and then flush with clear water.
Plainly, one must keep the water way from the control panel. Allow to dry or blow dry with compressed air, making sure the air jet doesn't push water towards the control panel.
Hope this helps.
Yours faithfully,
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Thanks much, Spook! I replaced the AC with another one I had, so I'm ready to try your bleach method.
On another note, the 940 is going to the shop tomorrow. Hoping for the very best with the car AC and all the other stuff I'm having done.
Wishing you a good night, and thanks again!
Susan
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Dear smfree,
Hope you're well. Glad you no longer inhale molds, etc.
I offered advice anent cleaning a window air conditioner because a driver's severe, hacking cough - that could cause a sudden lane change or improper turn - can jeopardize a smooth-running car!!!
I offer this explanation, lest I be held to have gone outside this Board's normal subject matter and so to have infringed forum rules.
Hope this helps.
Yours faithfully,
Spook
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Did you check for the broken solder connection on the control board? A very frequent problem. See info in FAQ.
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Hi Philip! Yes, I did, and I replaced the climate control unit. Then the wire was jumped. All worked well. I guess I could either try jumping it again or take the board back out.
If there were something wrong with the CCU, could it still make the clutch engage when "jumping"?
Seems weird. Jumping it works. New switch doesn't make clutch engage. Where could be the root?
Thanks so much for your reply! It is SO hot in PA right now!!!
Susan
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Philip, I said I replaced the climate control unit, but what I meant that I just reinstalled it. :)
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Dear smfree,
Hope you're well. I'll bet the problem is in the wiring connector housing, that brings power to the switch on the receiver/drier (the can-shaped device in the engine bay, onto which the low-pressure switch is mounted).
I suggest two possibilities: (a) the connector's contacts are corroded and/or (b) the connector's housing no longer holds the wire terminals firmly, so that when the connector housing is pressed onto the switch body, the wiring terminals do not seat onto the switch's contacts. Either or both of these conditions could have created a situation, wherein "jiggling" the wire created a connection, causing the compressor to engage.
As to corrosion, a layer of corrosion a few molecules thick - far too little to be seen even with powerful magnification - can block the flow of current. An aerosol corrosion-remover - e.g., DeOxit (https://www.amazon.com/CAIG-DeOxit-Cleaning-Solution-Spray/dp/B0002BBV4G ) - is required to dissolve the corrosion. De-Oxit penetrates and flushes away the corrosion. Others may have different corrosion-dissolvers that they prefer.
If cleaning the connector's contacts does not restore function, then inspect the connector housing. it may be broken internally, such that the housing no longer firmly holds the contacts at the end of each wire. It may be possible - using a small, needle-nosed pliers - to push each contact in the wiring harness housing onto its switch contact. If so, then the compressor should cycle.
I ran into this problem - an internally failed wiring connector housing - with an in-block engine temperature sensor. I used a neddle-nose pliers to push each wire contact onto the sensor. That has not since been a problem.
Hope this helps.
Yours faithfully,
Spook
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Hi Spook!
The fittings were sprayed with the anti-oxidizer stuff, but the clutch still doesn't engage.
I put a paper clip on both metal pieces of the black connector that plugs into the cycling switch, and the clutch started spinning immediately with just the ends of the paper clip touching the two spots. Tried connecting the black connector onto the accumulator, and the clutch wouldn't engage.
UGH. I'd think that since the paper clip works so well, there's no way that the clutch wouldn't engage by connecting it to the cycling switch. So it must be from the accumulator downward, wherever that goes?
Any thoughts are appreciated!
Wishing you a good week,
Susan
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Dear smfree,
Hope you're well. Your tests show that: (a) the compressor is fine; (b) the climate control unit is fine; and (c) the wiring connecting these items is in good order.
It is just possible that the new pressostat is defective, or, alternatively, that the accumulator (receiver/dryer) has failed such that the pressostat no longer can read system pressure.
I wonder if the compressor can run for long enough, to cause cool air to come from the vents. If there's inadequate refrigerant, the compressor may run briefly before its goes "off line".
Has anyone taken a system pressure reading? If there's too little refrigerant in the system, the pressostat will keep the compressor from running. In a low-refrigerant state, the compressor may run briefly and then shut-down as its own protective devices kick-in.
I think help should be sought from a shop that specializes in air-conditioning. You've done all of the things it is reasonable to do.
Hope this helps.
Yours faithfully,
Spook
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Hi Spook!
I appreciate your input. I will check into what you've said about the connector. I was fiddling with moving the wires to see if I could get the clutch to engage, and I couldn't. It was a very intermittent thing.
Is there any way it could be the accumulator, or are you definitely thinking it's something going on in the wire that connects to the cycling switch?
I might have to take it to the shop, as between this issue and the four loud clicks I just heard today when starting the car (it did start, but not before the four slow loud clicks, which may have occurred when it was turning over), and I'm becoming concerned since I'm driving this to AZ and back.
Thanks again, Spook! You've helped me a lot with this car over the years!
Susan
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