Official AC Thread

pmpalma · Post by **pmpalma** » 04 Jul 2007, 19:32

Further more... what's the purpose of that switch? Say by jumping it, will it make the clutch stuck defenetely? Just a matter of switching the A/C swithc on the ECC at off to turn it off?

I mean, why would someone go to all the extend of removing some shims from the clutch if by jumping the wires will do the trick? Besides keeping the safety of that thermal switch I don't see why... or am I missing something?

Post by **MadeInJapan** » 04 Jul 2007, 20:25

You don't want to jump the switch every time you have to use the A/C. If the switch is not engaging the A/C, then the most likely problem is low gas. The compressor not coming on due to the clutch gap is a whole different issue...even if you jump the switch, it won't come on if the clutch gap is too large.

Hippie · Post by **Hippie** » 11 Jul 2007, 20:37

I've read every page of this forum, and still have a question, if anyone can help

The A/C in the car does not blow cold air; (no flashing A/C or Recirc lights) it was initially checked by the mechanic to indicate that it did not need a charge (at least not then -- last summer when the A/C first crapped out). The compressor is not engaging....Recently, I unplugged the pressure sensor ( A/C High Pressure Sensor that functions off the "high pressure" side of the A/C system located next to the A/C Accumulator. I'ts function is to monitor the auxiliary cooling fan on and off or if the pressure in the system goes too high it shuts it down.). When testing that sensor, if not "plugged in" all the way, the compressor engages, WA LA, the A/C blows cold air. Tried this several times to be sure this was the problem....Unfortunately, tested it a little too much, since we then heard a LOUD whoosh - and was suddenly in a freon cloud (whoops - guess I'll be needing that system charge now, after all

).... Question is, based on the description of the function of the sensor - did it shut down the system because the pressure was too high -- if that's the case, how do I determine if it was, and why? OR was the sensor malfunctioning - is there a way to test the sensor to see if it was in fact the culprit? My wife is growing increasingly weary of driving the car with no A/C in the hot, muggy weather, while I enjoy the comfort of the A/C in my F250 pick-up

Any hints or suggestions?
Thanks for any help

UK850 · Post by **UK850** » 25 Jul 2007, 18:47

Hi,

I have been trying to fix a friends AC on their 95 Volvo 850 with Electronic Climate Control,

It has just been re-gassed by a friend at a local garage, (When it was re-gassed, it was done without the engine running),

The problem is that when you first start the car and turn the AC on it works fine, (Get's nice and cold),

But as soon as the rev's rise it cut's out and does not appear to cut in again,

If the AC has cut out it can take over 30 mins before the AC will start again (Engine has to be off),

I have noticed that when it is not working and you flick the AC switch the engine rev's rise by about 100-200RPM (indicating that the ECC is telling the engine ECU that the AC will be switching on), but the AC clutch does not engage,

I have replaced the AC relay thinking it might not be switching over every time,

I don't think it is the pressure dropping too low as when the AC stops running the pressure rises in the LP side to what is was before starting it off,

I do wonder if it might be the compressor getting too hot (I've not been able to do a from cold test)?

The UK haynes manual is very unhelpful as it doesn't detail any of the AC system, A circuit diagram would be nice,

Any idea's of things to check or a circuit/wiring diagram would be helpful,

Carl,

Post by **Ozark Lee** » 26 Jul 2007, 07:17

Sounds like a classic clutch gap problem. There is a good thread on the subject and its repair here:

Thermal Switch and Clutch

Be sure to check the PDF writeup in message number 4.

Another variation of the repair is here:

Ghetto Clutch Shim

The first method looks to be more proper but the second method looks much easier.

...Lee

volvoaddict007 · Post by **volvoaddict007** » 28 Jul 2007, 15:04

My '95 850 has a compressor that started making sounds, then quit blowing cold then started grinding so I bypassed it with a smaller serpentine belt ( w/o taking off the compressor by the way). Now I have the compressor from my '94 850 parts car out but all I know about it is it never made noises. When the parts car ( 135k miles ) was running , the fan motor wouldn't come on.

A friend ( commercial A/C mechanic ) can evacuate/recharge the '95 system. Is there a way to test this compressor and tell how old it is before I do this work or is this just a bad idea. I have more time than money right now.

va007

redsouther · Post by **redsouther** » 02 Aug 2007, 14:25

I thought I'd post my experience with the infamous "Clutch Gap" issue...

Several months ago I posted on here about a problem with the a/c on my 2000 v70. I had purchased it during the winter months, so didn't use the a/c much for a while after I bought it. However, due to the fact that I live in the hottest hell hole on the planet - central GA - I soon had need of a good strong cold breeze...

At first, the compressor would disengage after a long idle or during a hard acceleration, and never come back on. If I turned the a/c off, waited about 45 secs, and turned it back on, everything was fine. As the months went by, it became much more frequent. After posting on here, and reading several extremely helpful responses and posts - both here and on volvospeed - I decided to see if the clutch gap was the culprit.

I measured the gap, and sure enough it was between 0.8 and 0.9mm. I decided to go ahead with the "ghetto-fix" using plastic bread ties as shims - based on a post over at volvospeed - to see if that would solve the problem. My clutch plate design was a bit different from the one shown in his photos, but I was able to use the same basic principles. The plastic pieces were a bit too thick, so I "adjusted" them with a hammer. I used a flat-head screwdriver to pry the plate in, and wedged my shims into place.

After another round of "adjusting" the shims, I verified that I had close to 0.35mm all the way around the interface, and used an epoxy to secure the shims against sliding out. I cranked up the a/c and checked the pressure on the low port, just to make sure that wasn't an issue, and it showed a solid 46 pounds. It's been a week now, and the compressor has not disengaged once under very heavy use, during some very hot weather...

Now that I know that's the problem I plan to go back and remove the clutch plate and shims in order to do the repair correctly, but that's saved me a load of money!!

Post by **MadeInJapan** » 02 Aug 2007, 15:12

Good deal! Care to post up or at least give us the link to the "bread-tie" quick and dirty shim-gap repair? Of course, everyone needs to know that this is a stop-gap measure and isn't the correct or long-lasting repair.

By the way, someone a couple of posts back mentioned that their mechanic filled the gas in the A/C system with the car off and not running. This is NOT the correct way and you will not get much gas, if any, in the system this way. The car must be running, A/C on full blast (coldest setting and recirculating seems to work best)...the compressor needs to be engaged for the gas to go in correctly. Once all of these parameters are met, then you can attach the gas cans to the low pressure port and open them up. I should mention that I often put the can I'm emptying in a bowl of hot water to quicken the outflow.

volvoaddict007 · Post by **volvoaddict007** » 06 Aug 2007, 04:02

Thanks 3gGT,

I was seeing metal "dust" laying on the frame under the current compressor and the sound was happening all the time. It really sounded like it was going to lock up. Traveling in the middle of New Mexico prompted me to bypass it.

I will have the used compressor bench tested now that I know it can be done. For R & R, a mechanic was telling me to go from the top and remove the power steering pump and alternator. Is this necessary, or should I go from underneath with the jack stands?

Will be traveling Monday afternoon for 3 days ( with the 760/740 ) so won't be able to respond until then. Thanks in advance.

va007