20 replies to this topic

[merlin390]

This is on my mom's '96 854 GLT.

going down the road the AC works but once the compressor gets hot the AC stops(air coming out is hot). Pull over let car sit 30ish minutes and cool off AC blows cold again drive it and as soon as it gets hot no more cold air. The wonderful engineers didnt put a high pressure port (that I can find) on our cars so I cant hook up a manifold to it and read the pressures. any info would be greatly appreciated

-Will

[Bay13]

There is no HP port on the 850s. Using what you described could be the pressure switch on the back of the compressor, it's wired in series with the power to the compressor. To see if thats the problem reach down there and disconnect the routing through the pressure switch, just leave it out. If everything works fine after that, leave it disconnected, the new replacement rebuilt units don't have that pressure switch in there. There is a high pressure cut out switch on the HP line anyway.

[merlin390]

Thanks Rich, I am going home to Macon Saturday I will try it and see what I find.

I have got to find out why my AC isnt working in my car either....to Darn hot in these Georgia summers, the girls fuss about the no AC

[KLS]

If the pressure is high, that is because it isn't getting the cooling it needs. Either the condenser is dirty...bugs, dirt, etc., or because the condenser is partly full of too much refrigerant and not enough space remains to cool the hot gas.

Fix whatever needs fixing. If you've put too much refrigerant into the system, remove some until it works well. The right way is to remove all the refrigerant and add the correct amount by weight.


Ken

[Chris_R]

There is no HP port on the 850s. Using what you described could be the pressure switch on the back of the compressor, it's wired in series with the power to the compressor.  To see if thats the problem reach down there and disconnect the routing through the pressure switch, just leave it out.  If everything works fine after that, leave it disconnected, the new replacement rebuilt units don't have that pressure switch in there.  There is a high pressure cut out switch on the HP line anyway.

Cool! (No pun intended) I have the same problem and will give this a go.

Thanks!

[merlin390]

Rich I disconnected that switch and still was not right. I think I am going to take mine in and have the volvo place here in town look at it and tell me whats wrong. Dad still thinks he can fix mom's but I think he is going to screw something up


on my car the clutch on the compressor turns freely, I do not have that sensor on the back of my compressor. I am not sure if my system will hold a charge/vacuum but if i jump the low pressure sensor the ac compressor enguages but the air dows not get cold. I am going to hook up to my low pressure port and see what kind of reading I get and (if I can) evac the system and refill it and try it again. right now I am thinking the compressor might be screwed up (also the light on the dash for the ac doesnt light up) any ideas?

-Will

[Bay13]

For your car, cause the jumper of the LP switch causes the compressor clutch to engage, I'd say you are low on 134a. I'd hook up to an A/C machine, evacuate, then replace the schrader valve on the LP fill connection, then vacuum for at least 30 minjutes, then add tracer dye and 1.6Lbs of 134A.

[merlin390]

anything special about adding 134a to our cars?

[Bay13]

in the LP side, so you are adding vapor. If you have a machine in the shop just hook it up and use it. the key is add by weight, 1.6lbs. If you don't have a machine, then with an empty system, add two 12oz cans.

[merlin390]

I have to use the analyser first to make sure its pure 134a so I dont contaminate our bulk tank but we have a machine. I know what I am doing after work monday

[855T]

I'm having a similar problem. While on the freeway today, regardless of speed, it would blow cold until it randomly would decide to blow warm. A minute later, if I turned it back on, it'd get cold again.

[Bay13]

I'm having a similar problem. While on the freeway today, regardless of speed, it would blow cold until it randomly would decide to blow warm. A minute later, if I turned it back on, it'd get cold again.

could be low on 134a.

[merlin390]

Rich is there anyway I can fix the blown light that illuminates when you turn the AC switch to on?

[Chris_R]

Trick that Rich gave me before for charging the AC when using cans:
Keep the can upright and submerged in hot water. This allows the vapor transfer to continue.

Anyone have a pic/diagram of the pressure switch?

I poked around in there today but didn't see it.

Thanks!

[Bay13]

above is the LP switch, it's on the bigger line going into the firewall, the low side, thats actually the 134a vapor coming out of the evaporator, then it will go to the accumulator and then back to the compressor to be compressed and then sent to the concensor to be condensed to a liquid, then to the orface tube to be changed back to a vapor and let into the evaporator to take the heat out of the car and the cycle continues.

[xtonyx]

mine does it. im low on 134.

go grab a can w/a gauge on it for 20 bucks at the auto parts store and fill it up till the gauge says you're full.

Edited by xtonyx, 23 May 2005 - 05:23 AM.

[855T]

Uh, while driving today, it suddenly started blowing hot, felt like sticky air, then some vapor shot out of the vents. 10 minutes later, it worked fine, and proceeded to work fine the rest of the day. What the hell?

[Chris_R]

Mine just works great for approx 10 - 30 minutes (it's on it's own schedule).

Rich, when my AC shuts off should I try jumping that switch to see if it works again?

Otherwise where is this thing to bypass on the back of the compressor?

Thanks!




I swear my car is haunted or vexed or jinxed or plagued or something...

[noho]

Mine just works great for approx 10 - 30 minutes (it's on it's own schedule).

Rich, when my AC shuts off should I try jumping that switch to see if it works again?

Otherwise where is this thing to bypass on the back of the compressor?

Thanks!
I swear my car is haunted or vexed or jinxed or plagued or something... 

i know, i also want to know what the "high temp sensor" on the compressor looks like. ive looked above, under, and on the side of the compressor...i cant seem to see a circular brass thing or a white wire coming out of it as ive read one suggested.

does any one have a pic of this "high temp sensor" of the compressor?...could you please post it. its summer already...i need help!!!

[merlin390]

Rich, on my car I just hooked up the guages to the AC and this is what I have


77 degrees F outside

low pressure reads 50psi (car not running)

crank car up, turn AC on
@45PSI compressor enguages
@~25PSI compressor disenguages

turn car off let it sit and low pressure read 60PSI


I am about to evac the system right now and make sure it holds a vacuum


(I used our analyzer to make sure it was 100% 134a so I dont contaminate the
bulk tank)

alright. I pulled a vacuum for 30 minutes I couldn't see/tell a loss of vac on the guages.
started the car, jumped the low pressure switch and filled the system to 1.65lbs

at idle pressure reads ~35psi (compressor running) and the air coming out is a cool 39degrees F

I am willing to BET I have an leak somewhere (evap core ) but to the best of my knowledge the AC has never been touched before. I will keep a close eye for a decrease in the AC performance over time and periodically use the black light to check for leaks.

I LOVE my AC now that its working

Edited by merlin390, 25 May 2005 - 10:54 PM.