i just bought a 92 245 a two weeks ago. i knew the a/c wasn't working well, and now i'm trying to fix it.

my 92 245 w/ r134 a/c is cooling only very little. i did install an a/c clutch today, which works fine, and needed replacing.

after the a/c clutch repair, i observed the following.

1) the a/c is on, a/c clutch is engaged, i see one a/c line going in through the firewall freezing up.

2) i see no condensation discharge (water from the evaporator) under the car, and i felt the evaporator and it's not cool. also, the mechanical heater valve works and it is closed, so i can rule that out.

3) i thought it might be the expansion valve, but this system appears not to have one.

4) it appears to have freon, because the a/c line is freezing up, and the a/c clutch engaging when turned on.
i'm at a dead end.

evaporator clogged? high pressure switch/low pressure switch bad?

i would search for help, but the search engine is shut down.

i'm new to this upgraded system, and this system doesn't have a peep glass in the accumulator.

i have worked on earlier 240 a/c systems. i've completely R134-retrofitted my a/c in my 86 245, and it works great.

thanks again!!
byron golden
86 245, 1 owner, 245k+ mi
92 245, owner 2, 136k+ mi

The fact that the evaporator is not cold is definitely a problem. There are any number of bastardized A/C systems out there, mostly a result of mystery problems that people find a way around so that the thing makes cool air. No big deal, though, the 91-92 system on 240s is much better than previous systems, in terms of ease of working on it.

First, the expansion valve is actually an orifice tube, which is located in the smaller (high pressure) tube in the pipe junction approximately (read: approximately) halfway back on the right side frame rail inside the engine compartment. The pipe runs along side the frame rail and the orifice tube is in that junction. That same pipe continues, traveling upward into the evaporator.

Second, the fact that the pipe is freezing up is a problem. It is likely that the pressure on the suction side is way too low, meaning that the pressostat (a non-adjustable one in 1992, info courtesy of chrissij). The pressostat is likely either stuck, or has been disabled by having something cross-wire it within either the wiring harness or the wiring plug. It may just be stuck. On a good system, if you remove the pressostat, there should be a faint "click". Likewise, there should be a "click" when you install it on the accumulator again.

My personal guess, would be that the pressure switch is funky (or disabled). That can be verified easily using a low pressure gauge on the low pressure service port. If the pressure is below around 20, there is definitely a problem. Actually, a converted 1992 might only see low pressure as low as lower/mid-20s, since the pressostat isn't adjustable. Lower than that, the thing is stuck or disabled. Remove the pressostat from the accumulator, then plug the harness into it again. If the system works with pressostat removed, then there is a problem and it has been bypassed. You should not see icing.

Additionally, judging from the icing issue, the charge level may be low. Note, this may not be the case, but it pays to look at all angles before digging any depeer. Theoretically with a low charge level and very low low-side pressures, the pressostat should shut the compressor off.

Chris,

I am looking at purchasing a '90 240 with a few small problems, non-working A/C being one. I have used the Volvo kits to convert '87 740 and '89 760. I am quite happy with the perforance of both conversions.

Can you advise if the '90 240 uses an orifice valve system, or TXV system and can it be converted effectively without changing the condenser and evaporator coils? I have read here that some can be converted similar to the 740 or 760, but other model years require more extensive work. Not sure of which years.

Thanks,

Dan

The later model 240 series (86-90) requires more work to convert than does the 700 series Volvo, or the 91/92 240. However, that doesn't mean that it is impossible to have a decent conversion. Just that you should replace more things in the pre 1991 models than in the 91/92 models of the 240. Some of it depends on the climate in which you operate the car. A more basic conversion (new TXV, condenser fan) will do OK in cooler climates. Maybe tinted windows too. In hot climes, a new evaporator, new condenser, and condenser fan are very good. This rings up the expense, but a 240 is worth spending that kind of money on if it is in decent shape.

To answer your question, the pre 1991 models are TXV systems and take more work to convert. The later models (1991-1992) are very easy to convert and function well after said conversion, much like the 700 series is a good candidate for conversion.

The key, and I do mean the key for converting any system, is not to overcharge it! If you are barely at the minimum charge level recommended by the manual, you have enough (unless you live in 100 degree temps all the time). I just did an early-build 940 and charged fairly low. The thing functioned beautifully. The 240s that I did in the pre 1991 era, would usually put out vent temps in the mid-40 degree range on a hot day when cruising. A condenser fan helps a LOT. Keeping the airflow over the condenser is a major plus, and a cheap addition, without changing the evaporator. Also making sure that the heater control valve is closed, helps in a big way.

I forgot to add
1) the condensor aux fan does not come on when a/c is on
2) the clutch is getting very hot when the compressor is engaged
3) the compressor gets very hot.

i replaced the a/c clutch because the previous clutch bearings went out. the first clutch may have burned up because the compressor is getting very hot.

thanks.

There could be other issues at play here.

If you are sure that the condenser fan works properly (tested the circuit and the fan already) then there is likely low high-side pressure. this would mean that the high-pressure of the fan switch would never be triggered. The pressure is something like 180 for the switch on 240s, but I'm not positive of that. Anyway, if the charge is low, it would explain some things. The compressor will usually be pretty warm while running.

However, if the pressostat has been bypassed and the comp is running with a too-low condition, it is not getting oiled properly and would definitely run very hot. Also that would not be good for the long haul with the compressor either. The first thing to do would be to check the pressostat and then check charge levels/pressures, so that you know what you're dealing with. From there, the answer will probably be a lot more obvious.

One thing I don't like to do is to contribute to a wild goose chase. That said, check the easiest things first, since a lot of A/C problems aren't related to major component failure... until they've been overlooked or worked around.

Thanks Chris, quite informative.

so, if i understand you correctly, you are saying that if the condensor fan works but not coming on, then the high pressure switch is not triggering the fan on and the amount of freon is low.

questions:
1) could it be that my system is low on freon, not switching the condensor fan on, and with a bad or stuck high pressure switch (pressostat?)?
2) therefore, with this type of diagnosis, then would you say that i need to replace the pressostat and charge up the system?

i looked at the system quite closely, and it doesn't look like anything was bypassed. further, the pressostat (the high pressure switch?) appears rather new.

i'll test the condensor fan tomorrow & i can pull another high pressure sw from the junkyard. finally, i can charge the system up.

thanks again, byron

I would yank the high pressure fan switch (little side pipe off the high side expansion pipe) from the j-yard too. those things don't go bad too often.

I'm thinking that there is a problem that the system isn't cycling properly, hence the ice. Either that, or the pressure switch is really bad. You should see the accumulator sweat during hot weather, but you shouldn't see it icing unless there is a very low charge level and the pressure switch is bypassed... since pressure is directly related to evaporator pressure.

Also, yank the relay for the condenser fan from the junkyard. The relay rides along on the ignition coil bracket right near the ABS unit (if equipped) and the left side strut tower. Black relay.

Something about your system doesn't add up. Either the icing, or something. I'd get a set of gauges on it, especially in this case, a low side gauge (wal-mart if you don't have high/low pressure gauges available) to find out what the problem is. it sounds as if the low side is waaay too low.