Hi All, and thanks in advance for your help.

The AC in my 1992 Volvo 240 no longer blows cold air. Last summer it blew cold, and earlier this year it blew cool, but not as cold as last summer. The blower for the passenger compartment works fine, it is the temperature of the air that is the problem.

When I turn the AC on, the compressor will kick on for 15-40 seconds (ticking slightly while it runs), then turn off for a similar amount of time. I thought I might be low on freon but a gauge said I had about 30 PSI of freon, which showed in the gauge's "normal" range. My AC has been upgraded to R134 freon.

I thought the compressor was bad, but I realized that one of the pipes in the AC is getting ice cold. This pipe doesn't take long to cool down - less than a minute.

Does this mean that it is something other than the compressor or compressor clutch? That would be good news for me.

Thanks in advance,

Mark

 

I would have it checked for proper level. Those cheap guages do not really tell you anything. Just because it says 30 does not mean it is 30 PSI freon. It might only be air in there.

 

you dont mention wether or not the pressure is 30 with the sytem running or static. When the compressor runs the pressure is dropping to the low pressure limit switch setting and the electric clutch then disengages.It sounds like your system is low on freon and needs an additional charge. here is some info to totally confuse you
http://www.aircondition.com/wwwboard/current/44954.html

http://www.csgnetwork.com/r134apresstempconv.html

 

Thanks for the reply guys. I took it intoa local shop to have them check the freon level out and the system as a whole. They said it looked like something electrical and would continue their diagnostics to get to the bottom of it. That didn't make a whole lot of sense to me, but I'm not a mechanic.

They called back after a half an hour or so and said that it was something with the compressor. They said the repair, done correctly, would top $1000, which is in-line with another shop's estimate for compressor/dryer replacement.

However... during their diagnostics they evacuated my freon and added "a couple of pounds" of new "virgin" freon to the system. Now the AC works. All three pipes in my photo are now cold (the blue one is still the coldest). The inside AC blows cold too. I haven't taken it out for an extended drive yet to see if it really gets icy, but I'm happy for now. The tech said that the leak in the compressor would probably cause me to lose my freon before the end of summer, but I'm better off than before and only out $50.

I'm not sure how the one pipe was getting cold and the others weren't. I'm not sure how/why new freon would help. I don't see how it could be electrical, and if I had some sort of leak why there was "old" freon in it before. They seemed to either be poor communicators, not know what was going on, or hiding something, but I really can't complain.

Thanks again for your tips. I LOVE my 240 wagon and this forum, and the community behind it, helps me keep it on the road.

Mark

 

Boyles law explains why air conditioning works
http://www.grc.nasa.gov/WWW/K-12/airplane/aboyle.html
essentially, the compressor takes a low pressure gas and compresses it into a hot high pressure gas, as it moves through the condensor it changes from a high pressure gas into a high pressure liquid as heat is removed. this then moves into the reciever dryer wich removes any moisture that may have entered the system and acts as a resevoir for a continous supply of liquid to the metering valve/expansion valve. As the high pressure liquid is allowed to pass through the expansion valve it converts from a high pressure liquid to a low pressure gas there is an exchange of energy and as the gas expands it drops in temperature. this occurs in the evaporator and the blower fan moves air through the evaporator it chills the air causing the dew point to drop causing the moisture to condense on the coils and be removed thus cooling and drying the air in the vehicle...I am rambling here is a site that explins it also
http://autorepair.about.com/od/gloss...itworks_ac.htm

 

Same problem of trouble starting / stalling after wet weather 1991 Volvo 240

turned out to be caused by a worn crankshaft position sensor

 

8 year old thread.