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Blockage in a/c system? Comp. won't turn on 94 camaro

04colyZQ8 on Wed July 07, 2010 10:17 PM User is offlineView users profile

Year: 1994
Make: chevrolet
Model: camaro
Engine Size: 5.7L
Refrigerant Type: r134a
Ambient Temp: 80
Pressure Low: 25
Pressure High: 250
Country of Origin: United States

I had to jump the clutch relay to get the compressor to turn on, then I shut it of when the high side reached 250. Static reading was 130 psi both sides before I jumped the compressor. I think that the expansion tube is blocked? Or that there is some kind of restriction in the system. What should I do next? I would imagine the only way that the expansion tube would get clogged is from a falling compressor, so am I looking at a new compressor, accumulator, expansion tube and complete flush? Thanks -Jamie

htguru on Wed July 07, 2010 10:39 PM User is offlineView users profile

whats the low side doing?

mk378 on Wed July 07, 2010 10:48 PM User is offline

Plug everything in as stock, reset the computers by disconnecting the battery for a time, start the car and see if it engages then. If not, find the electrical problem. If a vehicle has electric fans and you jump the compressor so the fans don't come on, there will be abnormally high high side.

04colyZQ8 on Thu July 08, 2010 12:25 AM User is offlineView users profile

Aren't those reading incorrect? Low side 25 high 250 for 80 F temp. So you don't think there is a blockage? Also leading up to this the a/c seemed to work intermediately and on cooler days the clutch would kick in, when its hot the clutch never kicks in. I have owned the car for two years, never added freon and it just recently stopped working properly. I checked the fuse and replaced the relay I would like to know how to check the pressure switch there are 3 wires going to it, ground, 5v volt reference and a another wire can I check this with a multi meter? And is 130psi at rest normal it pegged my low pressure gauge to where it says warning!

04colyZQ8 on Thu July 08, 2010 12:33 AM User is offlineView users profile

also not sure if this has anything to do with the problem. but I reprogrammed the computer 6 months ago. I was running hot in traffic when I had the a/c off, the car would not turn the second fan on until it almost reached the red mark. I re-programed the second fan to turn on earlier, but left AL the a/c settings for the fan as normal. I also deleted skip shift than re-flashed the computer. The a/c worked great after this and the car didn't come near to over heating. just thought I would through that out there just in-case!

GM Tech on Thu July 08, 2010 8:19 AM User is offline

Early fixed displacement compressors on Camaros have an a/c algorithm that shuts down the compressor when low refrigerant charge is detected (because of a leak--shaft seal is number one location). So yo need to clear your code 46 with your Tech I, (or unhook battery for 10 sec) and try again--- 250 head pressure is normal- 425 is high and where the car shuts off the a/c for a hpco event. but only if you are not "jumping it" Your 3 wire transducer measures high side system pressre continuously - it is not a switch! cannot be jumpered! You can read all three wires with your DVOM....5 volt feed, ground, and 0-5v return signal-- why do you suspect the transducer?

65% of mobile a/c failures are due to lossof refrigerant due to a leak--- have refrigerant recovered and weighed-- most likely you'll find you have 1/3 of wha it needs in it and your system has shut itself down to save the compressor- you'll see an a/c code 46 with your scan tool--- clear code, fix leak (shaft seal), evacuate and harge to spec and you will be cool......I do it everyday--- just giving you the highest probability of what is wrong...

BTW ou have an "H" block TXV mounted on front of evaporator housing box underhood--- and it is NOT clogged and your pump is good-- based on your quoted pressures.....just give the pump something to wouldn't want your well pump to run dry at home when the well goes dry-- it would soon wear out your pump-- same with your car- system shuts down to save you money.....

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......

04colyZQ8 on Thu July 08, 2010 3:18 PM User is offlineView users profile

Ok thanks for all the great info! I reset the computer a/c turned on and worked great! Any way I can top up the system without recovering it? Can't I watch the high and low gauges and just add a little r134a at time? How hard is it to replace the shaft seal? I replaced the clutch about three months ago and have the proper tools for that. ounce it is removed, and the r134a recovered, what is the next step?

k5guy on Thu July 08, 2010 3:31 PM User is offline

The right way to do this is to recover and weigh the amount you put in. Part of the process is to draw a vacuum when you are about to recharge, and that usually can tell you if you still have a leak in the system. In old style CCOT systems, you could add some by calculating pressures, but in a computer controlled AC or TXV I wouldn't attempt it.


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04colyZQ8 on Thu July 08, 2010 4:00 PM User is offlineView users profile

What does CCOT and TXV stand for? I am not sure which system the 98 caviler had, but on that one the, compressor relief valve blew and spilled refrigerant everywhere, there was nothing left in the system so I replaced the compressor with one out of a wrecking yard, installed a new drier, orifice tube, flushed the system out, and added the proper amount of oil, vacuumed it down to 29 inches for about 45 min then recharged with durracool 12a. I estimated about 9 ounces was required according to there chart and I watched both gauges while I added a little at a time. It seems to work good. I am just afraid what I will get charged if I go to a a/c shop I would like to do as much of the work my self as possible

ACProf on Thu July 08, 2010 6:43 PM User is offline

CCOT -> Cycling Clutch Orifice Tube

TXV -> Thermostatic Expansion Valve

04colyZQ8 on Fri July 09, 2010 8:41 PM User is offlineView users profile


k5guy on Wed July 14, 2010 3:10 PM User is offline

While you might find using Duracool 12a works for you, you won't find many supporters of it on this site. This site is made for people that want to do it themselves, no matter the reason. The more you know about your car, how it works, the better decisions you'll made, even if you take it to have it serviced professionally. For more reading on Duracool 12a, see what the EPA says:


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04colyZQ8 on Thu July 15, 2010 12:50 AM User is offlineView users profile

04colyZQ8 on Thu July 15, 2010 1:02 AM User is offlineView users profile

The problem is that r134a is not available in my area any more, they only sell it to licensed shops in a 20lb bottle. I had to go to the states to get a couple of 12 ounce r134a cans to top up my camaro. All you can get here are 12a duracool and they sell it everywhere! So how can it be that bad? It is basically a propane mix right? Better for the environment they say, and if you get in a accidents it will most likely start a fire, but than again comp. oil under pressure hits a exhaust manifold with r134a will start a fire as well. Sure Duracool doesn't cool as well but we don't see the high temps in them summer such as most climates do.

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