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pressure sensor ?

WanaBeCoolAgain on Tue July 01, 2008 6:38 PM User is offline

Year: 1998
Make: chevy
Model: s=10
Engine Size: 2.2
Ambient Temp: 101
Pressure Low: ?
Pressure High: ?
Country of Origin: United States

pressure sensor, relay, low pressure or....?
It's me again wife called after she got to work said there was no air. i freaked!!
talked to my mach told me to bring it in when she got home to check for leaks i told her to NOT run the air on the way home. she called me on the way home said it was working fine. she has asama can't handle air hotter then 90, 95. after she got home i went out to the truck it was off for 3,4 minutes. when i engaged the air it took 30 seconds or so for the clutch to kick in. i turned the air off and on 4, 5 times the clutch kicked in right away. the vent temp seemed to be fine. i didn't test the temp.
Any thing i els i need to look in to?

mk378 on Tue July 01, 2008 7:29 PM User is offline

Clutch gap. Check that it is not more than 0.02 inches. You could pre-emptively close it up some as long as it doesn't rattle or drag when disengaged.

Intermittent problems are the worst, you really need to catch it in the act to diagnose.

It's not low on refrigerant because when it did engage, it worked fine.

WanaBeCoolAgain on Tue July 01, 2008 7:49 PM User is offline

I forgot one thing.. and i don't know if this matters.. the idle didn't change ether till it kicked in.
And.. the pressure sensor was left in the line when the A/C shop cleaned them. i asked if it needed to be removed and i would do it on the spot. but they said it was ok in the line when they did the job.

Oh you say adjust the clutch if it's more the 0.02.. so it is adjustable? if so how..?
Thank You

WanaBeCoolAgain on Tue July 01, 2008 8:04 PM User is offline

Well.. the more i engage my pee brain here. thinking im not getting a high idle till the clutch kickes in.
Should i be looking at voltage to the pump? if theres no voltage to the pump then go to CK the voltage
at the sensor. if theres voltage there look at the relay? thats after i have a look at the clutch gap.

and am i looking for 12V on all this stuff right?. And if i get to the really can i jump it? or robb peter to pay paul meaning like the swap relays if i have 2 of the same.



Edited: Tue July 01, 2008 at 8:06 PM by WanaBeCoolAgain

mk378 on Tue July 01, 2008 8:04 PM User is offline

If the engine doesn't rev up it sounds like a control problem, not the clutch. The truck is not even trying to start the compressor.

On a GM compressor you need the "clutch plate installer" special tool to force the plate further on the shaft. It's a friction fit. It would be good to have a "clutch plate remover" handy as well in case you go too far.

WanaBeCoolAgain on Tue July 01, 2008 8:09 PM User is offline

Quote
If the engine doesn't rev up it sounds like a control problem, not the clutch

meaning the stuff in my the reply above?

WanaBeCoolAgain on Wed July 02, 2008 3:31 PM User is offline

ok this morning it worked when the wife was on the way to work she called me at 11:00 AM telling me it wasn't working again and she was on her way home. she gets home shuts the truck off. i go out there and it's working! BLAH! it pulled down to 40 at a idle i swapped the horn relay with the A/C relay the A/C repay was very hot. don't know if it's supost to be but it was. the only thing that was changed on the A/C job was the pump. this wasn't a problem before the other pump took a dump.
so.. so if the truck is shut off and restarted it works and the pump was the only thing replaced.
Any other thoughts?
Thank You

mk378 on Wed July 02, 2008 5:06 PM User is offline

GM Tech would know, but maybe the PCM on that truck can hold some A/C related trouble codes. They won't turn the CEL on; you'd have to scan it.

At least it appears she can work around the problem by pulling over and restarting the truck.

WanaBeCoolAgain on Wed July 02, 2008 11:24 PM User is offline

Quote
At least it appears she can work around the problem by pulling over and restarting the truck

thats what i told her.. after swapping relays i took the truck out to do service calls.. drove 100++ miles
no problems i put my little temp gage in the vent it got down to 28 or lower after about 30 minutes of FRWY driving. after getting home and telling the wife she took it out about a hour later i heard the pump kick i as she pulled away. if it does it again i will have a look at the low presser switch. are they cleanable?
Again Thank You

WanaBeCoolAgain on Thu July 03, 2008 8:51 PM User is offline

Ok this is pi.... me off. today i make a couple pit stops in town run time about 25, 30 minutes. the fricken vent gage only got down to 60 and that took a while outside temp was 100,101. i get home and let it run about 10 more minutes in the drive way 60 was all it got down to. i poped the hood to have a look at the accumulator it was cool to the touch not freezing or cold.. i just drooped the hood and went in the house totally discusted.
Now what?
Thanks

Chick on Thu July 03, 2008 9:44 PM User is offlineView users profile

Your truck uses a "three" wire pressure transducer, make sure the connection is tight. Sometimes they get loose, a wire gets brittle, or may not be tight after changing the compressor, the transducer receives 5Volt reference and the computer tells the relay to kick in. You may have a bad transducer too. I believe there is a shrader valve under it, get one from a junk yard and swap it, new relay too, check for the relay being loose also..And of course the clutch gap. The compressor does not cycle....Hope this helps..

One other thing, GM tech had posted a pic of the wiring harness on the four cylinder engine where it gets crushed between the compressor and the intake. I can't seem to find it, but do a search under GMtech and maybe you can find it, if not he'll be along to repost it..I'll keep looking for it..Hope this helps..

Found it. Photo curtesy of GMtec



-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

Edited: Thu July 03, 2008 at 10:00 PM by Chick

WanaBeCoolAgain on Fri July 04, 2008 4:20 PM User is offline

clutch is engaging still same temp Blah!! i turned off the truck un plugged the low pressure cencer it didn't engage as it shouldn't plugged it back in the clutch engaged. I haven't looked in to the wiring but i did have all the stuff off when i replaced the pump. this is just a pisser. day before 40 at a idle. 28 after 30 minutes of FWY driving.
Happy 4TH to everyone and hope it's a safe one.

Chick on Fri July 04, 2008 4:40 PM User is offlineView users profile

You are going to need the pressures. You could have a leak, and with variable displacement compressors, the pressures will begin to equalize if the refrigerant level is low. The clutch is engaging, so that rules out electrical..now you need the pressures if the system isn't cooling. I thought you were having problems with the clutch kicking in??? If the system is full (only way to know for sure is have the charge weighed) then you have a control valve problem, pressures are still needed to determine that..No use fooling with it until you can get the pressures.. But you can still check the wiring for the "intermittent" problems if you still have those..Hope this helps..

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

WanaBeCoolAgain on Sat July 05, 2008 2:17 AM User is offline

sounds good i will give that a second look. i was thinking valve as well and a posible leak.. i didn't go nutts hurking the stuff togher. i didn't want to over tighten stuff and cause a leak that way. so i will bug my Mechanic tomarow
see if he has the time to give it a look.
thank you
hope everyone had a great 4th.

WanaBeCoolAgain on Wed July 09, 2008 4:06 PM User is offline

sorry i haven't gotten back sooner.. been sick. took it to the shop that charged the system after the rebuild. asked if he could look for leaks.. well he put the gages on it. Said it doesn't have a leak but it's taking forever for the pressures to get to where they belong heres the kicker..the vent temp went down to 45. still 5 degrees warmer then before but 15 degrees cooler before this started to happen he had me turn off the A/C and watched to see that the pressures equalized and they did told me the orfis tube was ok. he thinks the pump is going out the NEW pump. i paid a auto A/C company to flush everything
out when i did the the new pump and accumulate. used pag 150 that came with the pump kit. new orfis tube. when i had the stuff flushed i took the evaporator in to be flushed as well. 1 thing and i can't remember what the valve is called or if it has anything to do with this %@@@#%&^**(_ but can that be the problem?
this is ah pissen me off.
Thank You in advance

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