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Compressor not running. . . . .


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ratrace2
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May 16, 2010, 8:52 PM

Post #1 of 15 (1663 views)
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Compressor not running. . . . . Sign In

Hello Race Fans,
I'm running a 1998 S-10 Chevy Pickup (2wd) automatic transmission (M30) with a 2.2L (mfi) Vin 4 (LN2).
With 20080 miles on the speedo. "you could eat your egg sandwich off of it in the morning". Well, it's getting there.


The issue for the day is: the compressor will not run by itself and the A/C is blowing hot.



OK, I put 12oz of R134a with Florescent trace (that black light green stuff) in the Low side.

I got some gauges and I'm getting 38 low side and 370 on the high side. The compressor will not run without jumper wires from the battery. And the A/C does cool at the inside vents when I jumper the compressor clutch.

Actually, if it weren't for the jumper wire needed to keep the compressor running the system would be fine. I couldn't find any trace (florescent) coming from any joints or, I couldn't detect any leaks with a UV light.

Test: maybe we should put a DMM on the electical socket at the compressor or back up further........


Thanks all RR2


Hammer Time
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May 16, 2010, 9:34 PM

Post #2 of 15 (1659 views)
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Re: Compressor not running. . . . . [In reply to] Sign In

NOOOOOOOOOOOOOOOOO!
Take out the jumper

It's probably shutting itself down from over pressure. 370lbs of pressure is going to lock that compressor up in a heartbeat.

You need to find out why that pressure is so high. You either have a complete restriction in the system or you have no condenser fan at all. It can't run without a strong fan. That pressure needs too get below 275 and you still don't have enough refrigerant in it yet so the pressure will go even higher.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on May 16, 2010, 9:55 PM)


Sidom
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May 16, 2010, 11:39 PM

Post #3 of 15 (1651 views)
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Well sounds like you overcharged it, either that or it's around 130° today where ever you live.

1st rule with a/c is never blindly throw freon in. Take a static reading 1st, anything over 50psi should be enough to overcome the cycling switch & turn the system on.

Sounds like you have another electrical problem. Start at the a/c clutch relay. KOEO you should have power at 2 terminals. #30 & #85, both of these should have seperate fuses, the one for the load side is usually a higer rating.
Term #87 is the feed to the clutch. Run a 10a fused jumper to 87, if the clutch engages, everything is good in that circuit. Take a voltmeter & hook the pos probe to a 12v source, probe term #86 with the neg probe. There should be no reading, turn the engine on & then the a/c, it now should show 12v, thats shows the VCM is grounding the control side of the relay.

You're missing something on one of those circuits....I'm going off memory here (never a good thing) & sometimes manufacturers switch #85 from power to ground but 85 & 86 is the control side of the relay, one will have power the other is for ground and the one the VCM will use....( the relay should have a schematic on it). If by chance ever term does check out, try swapping relays, you may even want to try a swap 1st

If there is no ground the next step would be to verify the a/c request to the VCM, I'm not sure of a good way around this without a scanner. Maybe someone else has a good trick for that, that they will post....

Actually before you do any of that you need to get the freon pulled out of the system and charge it with the correct amount before turning the system back on with a fused jumper........






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(This post was edited by Sidom on May 16, 2010, 11:46 PM)


ratrace2
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May 17, 2010, 8:30 AM

Post #4 of 15 (1644 views)
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In Reply To
NOOOOOOOOOOOOOOOOO!
Take out the jumper

It's probably shutting itself down from over pressure. 370lbs of pressure is going to lock that compressor up in a heartbeat.

You need to find out why that pressure is so high. You either have a complete restriction in the system or you have no condenser fan at all. It can't run without a strong fan. That pressure needs too get below 275 and you still don't have enough refrigerant in it yet so the pressure will go even higher.



ratrace2
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May 17, 2010, 8:38 AM

Post #5 of 15 (1643 views)
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In Reply To
Well sounds like you overcharged it, either that or it's around 130° today where ever you live.

1st rule with a/c is never blindly throw freon in. Take a static reading 1st, anything over 50psi should be enough to overcome the cycling switch & turn the system on.

Sounds like you have another electrical problem. Start at the a/c clutch relay. KOEO you should have power at 2 terminals. #30 & #85, both of these should have seperate fuses, the one for the load side is usually a higer rating.
Term #87 is the feed to the clutch. Run a 10a fused jumper to 87, if the clutch engages, everything is good in that circuit. Take a voltmeter & hook the pos probe to a 12v source, probe term #86 with the neg probe. There should be no reading, turn the engine on & then the a/c, it now should show 12v, thats shows the VCM is grounding the control side of the relay.

You're missing something on one of those circuits....I'm going off memory here (never a good thing) & sometimes manufacturers switch #85 from power to ground but 85 & 86 is the control side of the relay, one will have power the other is for ground and the one the VCM will use....( the relay should have a schematic on it). If by chance ever term does check out, try swapping relays, you may even want to try a swap 1st

If there is no ground the next step would be to verify the a/c request to the VCM, I'm not sure of a good way around this without a scanner. Maybe someone else has a good trick for that, that they will post....

Actually before you do any of that you need to get the freon pulled out of the system and charge it with the correct amount before turning the system back on with a fused jumper........


I'm starting to think the wiring harness is junk.
I start my DMM testing today, and see what I can find out. This is going to be alot like the Fuel Tank Pressure switch, that's what it looks like.

What is the VCM?________

All right, I'll start up at the clutch and work down through the relay and to the ecm.....

Thanks, Guys I'll be back in a couple of days......I gotta re-read that haynes A/C manual....

You guys know of any good A/C Diagnostic videos or books let me know....



Hammer Time
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May 17, 2010, 9:48 AM

Post #6 of 15 (1638 views)
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I have to tell you again that with the high pressure your showing, the system will go into shutdown anyway. Your problem is likely not electrical at all. You have to find the reason for the high pressure first.

You said you put one 12 ounce can of refrigerant in it. If the system was empty when you did that, then it's not overcharged. If it already had refrigerant in it when you did that, then it could be overcharged but the low side reading doesn't really reflect that. Could be fan or plugged condenser.

Sidom has given you some good electrical info but he also said to resolve the pressure issue first.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on May 17, 2010, 9:50 AM)


ratrace2
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May 17, 2010, 11:04 AM

Post #7 of 15 (1631 views)
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OK, pressure issue first.....


Last Gauge reading (Monday 11:30 am) Low 30--High 250. Temp 70 degrees (Somerset, NJ).

Compressor still not turning on by itself.......................


(This post was edited by ratrace2 on May 17, 2010, 12:13 PM)


Sidom
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May 18, 2010, 1:16 AM

Post #8 of 15 (1619 views)
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HT has a real good point about the pressure.... I was assuming the system was full and you added a can cuz it didn't work.... See that a lot.

That head pressure is still too high for that ambient temp but the system should come on. It's possible you got a couple of things going on but 1st you need to get the system to come on....

Real quick grab a paper clip and jump the cycling switch on the accumulator and then the high pres cut out switch, it's either on the comp or the liquid line. If either of those get the system to turn on then that switch is bad. Then swap the relay with another one in the box

If none of that works, you really need to start at the relay. With a power probe (or equivalent, test light, jumper & dvom) within a minute you'll know what circuit the trouble is in...... 2 terminals should have power with the KOEO (#30 & #85)

The VCM is the vehicle control module, it's what turns on the a/c. You push the button on the control head & the VCM see's the "a/c request" and then decides if you can have a/c or not. It looks at its to do list and if something isn't done, it won't ground terminal #86 of the a/c clutch relay & you don't get a/c.






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ratrace2
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May 19, 2010, 11:03 AM

Post #9 of 15 (1606 views)
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__________________A/C compressor cycles on demand___________________
_________________Inside vents blow cold air___________________________


Well, where do I begin.
1st, the wiring harness going across the back of the motor has a burned area and expossed wires.
I taped and repaired the raw wires in the harness.
2nd, a/c fuse inside the Under hood relay box was blown, I replaced with a new fuse.
3rd, swapped relays from a/c and starter...........

Pulled down the volume of R-134a in the system....just seemed to be hot air anyway.

Now it works, the a/c that is.
..................................................................................................................................................
Next:
KOEO: manifold gauge reading 50/50 low high.
Inside vents blow cold air, not real cold.....but it's only about 68 F this morning.

Axillary issue:
Compressor bearing making a loud whining noise, will look into changing that next week.
and, that is the only thing left that is actually wrong with the truck. Just a loud/whining compressor bearing.

All other things have been fixed: brakes, wheel bearing/races; exhaust; FTP; A/c; starter; water pump; inner/outer tie rods, center link, idler arm; front tires; fuel filter, air filter, oil filter; grease job; serpentine belt; All water hoses; new battery; brake system complete overhaul;. . . . . etc. . .etc. . .etc. . . .Runs like new.

Other than just changing the compressor bearing because doesn't sound cool, the truck repairs are done.
I was thinking, I got this fixed a lot faster than that FTP sensor....

Thanks much guys......wow you guys saved me a bunch of cash.....Time and trouble......I owe you guys big.


Hammer Time
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May 19, 2010, 11:11 AM

Post #10 of 15 (1602 views)
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You seem to be treating that bearing as a very minor thing. That usually means a new compressor, depending whether it's the pulley bearing or the front compressor bearing. Either way I would change the whole compressor and flush out the system.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ratrace2
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May 19, 2010, 11:25 AM

Post #11 of 15 (1599 views)
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Actually: let's run a test.

ambient temp: 68 F

Gauges on the truck: say,

1. KOEO: low 100, high 100
_________________________________________________________________________________
2. Engine Running, A/C on full blast, fans on full blast; compressor running...
Low 20-25 , High 150
3. after about 2 minutes
Low 25 , High starting to climb, and is climbing to 225.
----high side discharge line getting really hot-----

I'll have to study this...


Hammer Time
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May 19, 2010, 11:37 AM

Post #12 of 15 (1596 views)
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Those pressures are'nt bad at first. It looks like it's still a little low on refrigerant but the high side rising is a problem. You could have a fan problem or a restricted condenser. The discharge line getting hot is normal. The liquid line coming out of the condenser should be warm to the touch. Not hot, not ambient.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



ratrace2
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May 19, 2010, 9:30 PM

Post #13 of 15 (1586 views)
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Getting closer.

You just changed my thinking on that compressor bearing, I didn't think about that. I was just thinking of it as a fan belt pully bearing.....Hu.... If the problem is with the compressor shaft, that is a real problem.......

Today, I ordered a new Orifice tube. I going to change that first and flush the Condenser.
Then, I'll see what the pressures look like. This (this job) is also an experiment that will let me learn about A/C
Systems without putting a new system at risk. At least this way, If I really screw it up I only Killed a compressor with
200,000 miles on it.

Oh yea, I went to the Chevy dealer here (Malouf) because I wanted to know what type of compressor was on the the truck. I think it is a V7 but it looks a lot like an HT-6.....They didn't know. Also, I wanted to know what type of PAG oil that the compressor took, they didn't know, they just wanted to sell me 8 0z ($33.80) of Universal PAG oil. I know there are 3 different types of PAG oil on the market, And Chevy can't tell me which one goes in their compressors.....

I looked in Alldata but I couldn't find the type of compressor or the type of PAG oil that the system takes....YOu know???

Thanks much, RR2


Hammer Time
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May 19, 2010, 9:42 PM

Post #14 of 15 (1580 views)
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The oil isn't really different. It's just different weights. I use Pag46 in just about everything. GM sell a synthetic Pag that they recommend using too. Your doing the right thing with the orifice and flush. Make sure you vacuum it for a good 30 minutes and charge it with the proper amount. Also make sure the fan is pulling a good amount of air and has a good shroud.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
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May 20, 2010, 12:09 AM

Post #15 of 15 (1575 views)
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Good job on getting the a/c going....

Just skimmed the tread real quick (just finished 2 of training not much left) but looks like HT has got you going on the right track...

The only other thing I'll add is get the garden hose & clean the condsensor & rad, if you can look in between the 2 and make sure there isn't any debri in there but make sure you clean the consendsor real good.

I'm curious if fixing that harness fixed you ref v problem & you can eliminate the jumper.................






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(This post was edited by Sidom on May 20, 2010, 12:10 AM)




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