Sorry in advance for posting another thread.....

Heres the situation... My AC doesnt blow cold, when letting the car idle for an extended period of time, the condenser does NOT turn on. I bought the recharge kit and followed the instructions. It suggests that when the compressor does not come on to put in half a bottle and see if it turns on... ( how do i know where half a bottle is? idk ) But I put in quite a bit. After a while the compressor started to click on and off for a second at a time, but never fully on. The instructions also indicate that the psi reading is only accurate while the compressor is ON. When its off, the gauge was deep into the red, but when it clicks ON, the needle drops quickly, but i can not tell how far it would fall because then the compressor shuts off and the needle spikes again. Should i be afraid of over pressuring the system?

SO, short version...

1) Is my compressor toast/ out of shim ?
2) Do i just need to keep pumping in freon to get it to stay on fully
3) assuming i have a large leak or the system was near empty, would that explain why it took half a bottle to get anywhere at all?

 

Quick update... I tried the "broom handle" idea posted in the pinned re-shim thread... With the car running, and compressor not spinning, if i wedge a broom handle against the clutch surface and apply pressure, it comes alive and spins for a few moments. This means my clutch needs reshimming yes?

- also, im still afraid i over filled the system as stated above. Would it be wise to evacuate the system for the time being until i get an accurate reading?

thanks!

 

I would reshim the compresssor and take it from there.

 

Bypass the low pressure switch and check the pressure readings with the engine running and AC ON. Top it up as required and then reconnect the switch. Since the needle goes down as soon as the compressor kicks in suggests me that shimming is not the issue (appologies for contradicting Tech) becuase the compressor starts to pump. You might just be getting either a high pressure or low pressure shutdowns.

 

How do i Bypass the switch?

thanks guys

 

You would unplug the switch and put a wire between the 2 terminals.
It's ok Harry I suggested the shim first because 95% of the A/C problems lately are a combo of problems and the shimming is half the problem.

 

It *seems* to be running constantly now... ( with 2 cans of freon... ) BUT, the weather got cooler, so i haven't had the opportunity to try and kill it yet ( full blast for extended period of time ) ........... ill update.

 

ok. stupid question i realize. but it ur mixture vent open or closed? if its open on a hot day it would make the inside hot also.....

 

I was about to try and recharge my 97 850 through the port located behind the passenger headlight near the belts and got a reading of 100psi.

It was running for about 10 minutes prior to the check and I couldn't find another fill nipple. On the access cover it says "6Nm Max". Is this really the only access point because I've read others say 70Nm? If so does anyone know why when running the A/C on High that I've got 100psi at the nipple and yet no cold air? Any ideas on filling this A/C?

Thanks for any help,
-J

 

Nm (Newton Meter) is a torque specification for the cap itself. It has nothing to do with the system pressure. The only port on an 850 is the low pressure side port, there is no high pressure side port on an 850.

The reason that you have 100 psi and no cold air is that the compressor isn't running. The good news is that you have decent compressor off pressure so it appears that the system is not leaking and your problem is electrical. Try to jumper the low pressure switch and see if it comes on and, if it doesn't, check the terminals on the low pressure switch for voltage, one of them should have battery voltage.

If you have no battery voltage on the low pressure switch check the A/C relay - you need to pop out the glove box to get to that one.

If you have voltage to the compressor and it still won't engage then you likely need to re-shim the clutch.

Is this an electronic climate control or a manual?

One last thought, if you have an electronic climate unit, when the light on the A/C switch is lit the A/C is off.

...Lee

 

https://volvoforums.com/forum/album....pictureid=1112


Here's a quick pic of the A/C High Side Sensor.

Any ideas on the proper jumping procedure? I'd hate to fry this system with a miss configuration.

There are 3 wires = Purple/White Stripe
Blue/Orange Stripe (Middle Wire)
Brown/Orange Stripe



Here's a 10 page album I created for A/C compressor and sensor locations.

https://volvoforums.com/forum/members/artic_fox-25582-albums-volvo-1996-850-c-help-photos-156/

 

That is the high pressure switch, the low pressure switch is on the low side line that is next to the firewall. You might want to edit your other post.

...Lee

 

This is a manual A/C unit on a 96 850

Any ideas on the jumping of the 3 prong A/C switch? This is what I'm experiencing:

Turn car on and all connectors in place, connected as original
Turn A/C on
The Clutch is NOT engaging at this point
Car still running

Disconnect 3 prong A/C High switch connector
Clutch engages and disengages in a very timely fashion (~2 seconds periods of cycle on, cycle off)

Disconnect 2 prong A/C Low Pressure Sensor by firewall
Clutch stops cycling

Reconnect 2 prong A/C High switch connector
Clutch is NOT engaging anymore



Car is shut off and now restarted, A/C turned on
All is reconnected at this point
Nothing is happening at the clutch then after about 15 seconds it tries to rotate about 1/2", then nothing, no fan no more clutch movement

Disconnect 2 prong A/C Low Pressure Sensor by firewall
Cooling Fan spins up to the higher setting like normal when A/C is on
Clutch not engaging

Reconnect 2 prong A/C Low Pressure Sensor by firewall
Nothing is happening at the clutch then after about 2 seconds it tries to rotate about 1/2", then nothing, no fan no more clutch movement

Disconnect and Reconnect 2 prong A/C Low Pressure Sensor by firewall
Cooling Fan spins up to the higher setting like normal when A/C is on
Nothing occurs at the clutch this time at all. I have to kill the ignition and restart to get the clutch to turn 1/2" and then it works no more.
It appears that restarting engine clears the ECM of the fault to kill the clutch when the High Sensor (2 prongs) is connected.

Given this testing, how do I keep the clutch cycling like it supposed to and not every 2 seconds on and off?
Any ideas on the jumping of the 3 prong A/C switch, I'm afraid of frying the system?

 

What if you jump the 2 prong switch will it stay running?

The 3 prong is a major pain to jump because one wire controls the cooling fan one controls the compressor and one is ground.

 

When I jump the 2 prong the clutch engage for 1/2" turn then stops. Then I remove wire jumper and try again and now nothing, I have to restart car to get it to move again 1/2" when jumped.

 

When you do that the 3 prong plug is still plugged in correct?

 

Yes
2 prong jumped, 3 prong connected as normal

 

OK then something else is turning it off. Is the blower motor resistor new or old?

 

It has all original resisters, equip. If you connect the 2 prong and disconnect the 3 prong can it be jumped to lead to the problem based on the results?

 

Like I stated earlier it is a major pain to jump the 3 wire and if you do it wrong it will fry something. Can you find another blower resistor to try?