A/c compressor acting up
Thread Starter
Racer
Joined: Nov 2008
Posts: 442
Likes: 6
From: jacksonville Florida
A/c compressor acting up
Before I start worrying about evacuating the R12 in my system I want to confirm with you all what my A/c problem might be. I have had my 82 vette (all original or parts replaced to original spec as best as possible) since 2006. About every 3 years she has needed a top off of refrigerant, which i can usually tell cause my compressor will come on more often and the air temp will not be as cool. My father in law is a mechanic and usually had some R12 lying around I could use. In 2014 I topped off with R-414b from a buddy of mine who works on A/c units. It seemed to work just as good as the R12, compressor seemed to run for about the same length of time and good cool air. Well I went on deployment in 2015 and when i got back 10 months later I noticed that when i turn on the a/c the compressor will come on for much shorter duration, turn off, then turn back on again for a quick time (maybe 3-4 seconds tops), the air is also barely cool coming out of the vents which i assume is mostly because i dont think the compressor is staying on long enough to even get the fluid through the refrigeration cycle. Do you think my compressor has gone bad? Could it be a relay? What should be my next troubleshooting steps to diagnose the problem?
Thank you for your help
Thank you for your help
Team Owner
Joined: Jun 2000
Posts: 38,923
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From: Southbound
Cruise-In II Veteran
Thread Starter
Racer
Joined: Nov 2008
Posts: 442
Likes: 6
From: jacksonville Florida
Yeah, but what kind of a bill am I going to expect having a shop mess around with my R12? I know those 25lb cannisters go for over $300...
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Burning Brakes
Joined: Apr 2010
Posts: 1,018
Likes: 9
From: Winston Ga.
you have a hole in your system causing it to "short cycle"
it will need to be charged to find a leak, either with dye or (we use) electronic sniffers.
then the refrigerant can be recovered and the repair made and the system recharged.
thats how to do it correctly.
R12 is not cheap anymore, likely it'll be less to convert it.
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Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
most likely not a relay or compressor going bad, low pressure switch can be by-passed to find out if that is the problem, if still acts up when bypassed, then it might be a compressor or something else going bad, what relay are you talking about??? If you don't have someone that knows a/c repair, then you are going to pay someone to work onit. check witha local corvette club and find out if a member there might be able to help out. with out a manifold to check pressures etc., it kind of hard to help you.
Last edited by lvmyvt76; May 6, 2016 at 11:13 PM.
Burning Brakes
Joined: Apr 2010
Posts: 1,018
Likes: 9
From: Winston Ga.
cant rule out compressor because it may be leaking at the seals.
likeyly not a relay but cant rule it out. if the clutch is engaging at all it is likely good but if it is weak then it could still be a prob.
cant rule much out until it has pressure in it. You could bypass the pressure switch but that will just be more work since you will have to pressurize the system to find the leak anyway.
Thread Starter
Racer
Joined: Nov 2008
Posts: 442
Likes: 6
From: jacksonville Florida
Well I got my hands on a can of R12, as I was recharging the system, the compressor did not sound as healthy as I'm used to. Eventually it started squeeking and the A/c was barely getting any colder so I decided to call it. I now would like to move forward with converting the system to R134 in the best possible manner. Do I need to replace everything to do this? Or just certain parts of the system?
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
If you are going to convert to R134 there are a couple of ways of doing it. The simplest involves putting adapters on your fittings so you can get the R134 equipment hooked up, evacuate and recharge with an appropriate charge of R134. There is a conversion formula to calculate how much to put in. The better way of doing it is to replace pretty much the entire system. The hoses for R134 are different. The molecule is smaller and will eventually leak out through an R12 hose. The better conversion kits will include a modern compressor that is more efficient. There are a couple of conversion systems on the market.
Thread Starter
Racer
Joined: Nov 2008
Posts: 442
Likes: 6
From: jacksonville Florida
If you are going to convert to R134 there are a couple of ways of doing it. The simplest involves putting adapters on your fittings so you can get the R134 equipment hooked up, evacuate and recharge with an appropriate charge of R134. There is a conversion formula to calculate how much to put in. The better way of doing it is to replace pretty much the entire system. The hoses for R134 are different. The molecule is smaller and will eventually leak out through an R12 hose. The better conversion kits will include a modern compressor that is more efficient. There are a couple of conversion systems on the market.
Pro
Joined: Oct 2011
Posts: 743
Likes: 71
From: Jarrettsville Maryland
If your system has a known leak in it, it's actually illegal for a shop to top it off without fixing the leak.
I believe my system was first converted by just evacuating all of the R12 and oil, and putting in R134 with oil. It worked very well. Supposedly, used R12 lines won't leak R134 as unused lines will, as being used puts a coating on the inside of the lines that seals them.
My A/C worked great until my original compressor quit on me. Long story short, if you replace the compressor, get the AC Delco branded compressor (available on Amazon for less than shops will probably charge you for whatever brand they sell), as the other brands of compressor either didn't work right from the get-go, failed after a year, didn't cool as well, or any combination of those. While going through the compressor hassle, I also replaced all of my A/C lines, drier, put in a variable orifice tube, and installed a reproduction condenser that is a parallel-flow condenser designed for R134 (available from Classic Auto Air). My A/C is cold again, though the AC Delco compressor made the biggest difference. The rest of it needed replacing anyways, and I figured I'd replace it with stuff designed for R134.
I believe my system was first converted by just evacuating all of the R12 and oil, and putting in R134 with oil. It worked very well. Supposedly, used R12 lines won't leak R134 as unused lines will, as being used puts a coating on the inside of the lines that seals them.
My A/C worked great until my original compressor quit on me. Long story short, if you replace the compressor, get the AC Delco branded compressor (available on Amazon for less than shops will probably charge you for whatever brand they sell), as the other brands of compressor either didn't work right from the get-go, failed after a year, didn't cool as well, or any combination of those. While going through the compressor hassle, I also replaced all of my A/C lines, drier, put in a variable orifice tube, and installed a reproduction condenser that is a parallel-flow condenser designed for R134 (available from Classic Auto Air). My A/C is cold again, though the AC Delco compressor made the biggest difference. The rest of it needed replacing anyways, and I figured I'd replace it with stuff designed for R134.
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay