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Clutch engages. No cooling

AC Amiture on Mon June 02, 2008 5:32 PM User is offline

Year: 2003
Make: CHEV
Model: S-10
Engine Size: 1.5?4Cyl
Refrigerant Type: R-134
Ambient Temp: 103
Country of Origin: United States

Noticed Sunday afternoon that my AC was not cooling. Fans, but only hot air. Clutch will engage. No funny noises from the compressor. One hot hose, the other is warm (under hood temperature) so defiantly no cooling. There are some diagnostics that do not require gauges in my mastercool book. I will try these. Now that I have this trouble I remember that it did not cool well on the day before, it cooled but seemed to take a long time to cool down. Now it does not cool at all. I just wrote it off to the hot day at the time.

One thing that has me stumped, is that, if I have lost charge why doesn't the pressure switch keep the clutch from pulling in?

I will have access to gauges this weekend but would like to hear any thoughts you guys may have in the meantime. I will also try the diagnostics.

OH! Just to frost it off nicely (Pun intended) my daughter just called to say that the AC on her Mitsubishi, that I just, almost completely, rebuilt, is not cooling now. I'll be going by her place this evening to see what's wrong. I hope it's an easy fix....


I hope.......

I hope.......

GM Tech on Mon June 02, 2008 5:53 PM User is offline

Your V-7 compressor does NOT cycle- it is a variable stroke compressor- will run with as little as 4 ounces of refrigerant in the system- you are probably low on refrigerant- or your compressor is burnt up inside-- A quick check of the orifice tube can tell you if the compressor is okay-- An evacuation and weighed charge extracted will tell you how much is in the system--or you can try to add refrigerant to see if it starts to cool-- but your system has a transducer that watches system pressure to determine when to shut the compressor off- and until the system pressure drops below 47 psi- the compressor will run continuously whether or not there is any cooling-- this is by design...

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

AC Amiture on Mon June 02, 2008 6:55 PM User is offline

Thanks for the quick reply.

Kind of sounds like my symptoms.

" or your compressor is burnt up inside"

I hope not. My (limited) experience with compressors is that bad ones usually sound that way.

Since this one is quiet I'm hoping it's still good.

If I am low on refrigerant then I'll be looking for a leak.

The system is 5 years old but has be working well until recently.

I have located all of the major components but am not sure where the orifice tube is.

Can you help out with this ? How do you check it? pull it out and look at it? How hard is that to do?

THX

RAF

Edited: Mon June 02, 2008 at 7:02 PM by AC Amiture

mk378 on Tue June 03, 2008 2:49 PM User is offline

You probably have a leak, considering the loss of performance over a few days and also that the hose does get warm indicating the compressor is pumping a little. By the weekend it may all be gone and the compressor won't come on.

If you have a control valve failure (inside the compressor) the low side will be quite high, possibly with little difference between the low and high. The variable compressors often fail this way. They will still turn smooth and quiet but they don't pump like they should. The control valve can be pulled and replaced without buying a whole compressor.

AC Amiture on Tue June 03, 2008 3:09 PM User is offline

AC Amiture on Tue June 03, 2008 3:17 PM User is offline

Thanks for all of the advice. I'll start digging this weekend When I have time and gauges. I'm sure I'll have questions.

One right now is: Will anyone recommend some one on the east side (Chandler) who can do leak testing and will work with a DYI guy such as me?

By this I mean they do the leak testing and I will do the work once I know where the problem is.

I may not need this help but if I do it would be good to know who to contact.

HECAT on Tue June 03, 2008 3:51 PM User is offline

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AC Amiture on Sun June 08, 2008 3:29 PM User is offline

Well, Gauges on today. Engine running System ON. low side is 111. High side is 120.

This looks a lot like: "If you have a control valve failure (inside the compressor) the low side will be quite high, possibly with little difference between the low and high."

What advice do you all have?

Is this pretty conclusive or are there some other steps I should take?

"The control valve can be pulled and replaced without buying a whole compressor."

Where can I get some information on how to do this?

The compressor is marked: "DELPHI Harrison Thermal Systems" with two numbers 7023 and 15765204"

Is this a V-7 Compressor?

I still don't know where the orifice tube is located. Any advice?

GM Tech on Sun June 08, 2008 3:57 PM User is offline

It's either the control valve or a wiped out internals on the compressor-- My money is on the bum internals.

the orifce tube is in the loop as it goes into the evaporator- you have to remove the A/D to make for easier access- lokk for the connection and dimples in the liquid line from the condenser to the evap...

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

AC Amiture on Sun June 08, 2008 4:33 PM User is offline

I did a little research on the control valve and found a very good article on changing it but I can't find out where to get one. My searches come up with nothing. Any idea how to get one?

In the meantime I'll start pricing compressors.

"AD" = What?

AC Amiture on Sun June 08, 2008 4:35 PM User is offline

Also, if I replace the compressor what else am I going to have to replace, add filters etc. to insure that it lives?

mk378 on Sun June 08, 2008 5:51 PM User is offline

The A/D is the Accumulator / Drier. The big canister next to the evaporator.

AC Amiture on Sun June 08, 2008 7:40 PM User is offline

Thanks,

I'll Go hunting now. Any one Know where I can get a new control valve????

Edited: Sun June 08, 2008 at 7:43 PM by AC Amiture

mk378 on Mon June 09, 2008 12:04 AM User is offline

Recover the refrigerant, would be good to weigh it on the way out to see if it was properly charged. Then check the OT first, if it has bits of compressor all over it your compressor is toast so no need to bother with finding the control valve seperate.

AC Amiture on Mon June 09, 2008 1:27 AM User is offline

Good suggestion. I probably will have to wait until next weekend to do any more.

Thanks

AC Amiture on Mon June 09, 2008 1:41 AM User is offline

Good suggestion.

I'll probably have to wait until next weekend to do any more.

I used your advice and now I think I have the orifice tube located. It does look as though I will have to remove the A/D to get to it.

Is there a method of insuring that the clutch does not engage once I have opened things up?

I will probably have to drive the truck for a while after I have looked at the Orifice tube while I wait for parts. There is a connector near the front of the compressor that looks as though it would disable the clutch. I could also try pulling a fuse, if I can figure out which one.

I am assuming that there is a clutch on this kind of compressor that will allow me to keep the compressor from turning until I can close the system up again.

Thanks for all of your help so far.

Edited: Mon June 09, 2008 at 1:41 AM by AC Amiture

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