AC compressor not cycling

**collinsperformance** · 03-13-2007, 11:53 PM

ok, i am new to newer chevys so please do not beat me too much. i searched and found no matches so i ask here.
i got a 1993 K1500 4x4 with the 350/auto air front rear.
the ac worked fine the 1st 2 months of owning it. we made no ac or heat changes (minus the recycle door motor -see other post) well now if i put the ac to cold and hit the ac button the compressor will not cycle. i put a volt meter on the electric clutch connector and it never get a signal ( i planned on making a jumper to see if it engages but ran out of time today) the climate information box shows the ac liteup but it never cycles the compressor. i unplugged the other plug on the compressor and it looked ok and i unplugged the dryer sensor and it looked ok. i not sure where to go next it is warming up and i need to get this fixed for the wife so i can get ready for the next project a lift kit.....mike

**TrailLeadr** · 03-14-2007, 12:16 AM

Sounds like you might have a leak. There is a pressure switch. If your pressure is not high enough the switch disengages, and will not allow the pump to operate.
DON'T jumper the connection, forcing the compressor to run. If it's run while it's low on freon, it can ruin the compressor. The freon has oil in it to keep the pistons, and o-rings lubed as the compressor runs.

This may be a good time to take advantage of the fact that it needs to be serviced, and have it converted from R12 to R-134.

**Crawdaddy** · 03-14-2007, 10:21 AM

In a ford F-150 that I used to drive on occasion up at the boy scout camp, I had a similar problem. While a friend and I didn't have gauges to check the freon level, we were pretty sure that it was not low on freon. However, the clutch would not kick in for anything. We actually hardwired a manual switch into the clutch to manually kick it in, and still couldn't get the compressor clutch to engage. We never figured it out, and the truck had some serious other problems. It ended up dieing in an undeterminable way. The catalytic converters on it got red hot and the truck had no power or oomph to the motor, but I digress.. The A/C went all funky on us, and we never figured the problem out.

**TrailLeadr** · 03-14-2007, 10:32 AM

Originally Posted by Crawdaddy

In a ford F-150 that I used to drive on occasion up at the boy scout camp, I had a similar problem. While a friend and I didn't have gauges to check the freon level, we were pretty sure that it was not low on freon. However, the clutch would not kick in for anything. We actually hardwired a manual switch into the clutch to manually kick it in, and still couldn't get the compressor clutch to engage. We never figured it out, and the truck had some serious other problems. It ended up dieing in an undeterminable way. The catalytic converters on it got red hot and the truck had no power or oomph to the motor, but I digress.. The A/C went all funky on us, and we never figured the problem out.

Sometimes the coils in the clutch assembly fail.

Catalytic converter going red, and losing power sounds like imcomplete combustion. Maybe the coil wasn't putting out enough spark.

Sounds like that Ford definitely had some electrical issues.

**GaryL** · 03-14-2007, 10:38 AM

Trail Leader is most likely correct. Leaks in the a/c system are usually pretty easy to find. Check all of the lines and connections. If you find one that is greasy around a joint or connection, that is probably where your leak is. The oil in the system will attract and hold dirt where it comes out.

Post up your location and help may be closer than you think.

**unplugged** · 03-14-2007, 12:38 PM

I agree that it probably has a leak. I bought my 93 a couple of years ago and the AC quit working after 4 months. I had it recharged with R12 and it worked fine for a year. The compressor did crap out a year later so I replaced it. I was considering converting it to R134, but posts on the internet made me reconsider. (R12 supposedly is a better refrigerant.) Anyway my mechanic only charges $27.50 per lb. for R12 and it takes appx 5 lbs for a 93 burb with front/rear air. $30 x 5 = $150 vs replacing the filter/dryer and a bunch of o rings plus R134 at $6/lb. Estimate was about $350 for the conversion. Here is a site with some good info on the cost of a typical conversion: http://teamchicago.com/imperial/imp-ac.htm
So I currently am sticking with R12, but I may eventually make the switch if I keep the vehicle.

**Crawdaddy** · 03-14-2007, 01:09 PM

you're lucky your mechanic still has R12. They stopped making/selling that a few years ago. It polluted and ate the ozone up too bad. (see http://en.wikipedia.org/wiki/Dichlorodifluoromethane for more info; wikipedia, how did the world ever get along without it...) I'm not sure if my 'burb has been updated to R134, but I have some A/C work to do in my future, my rear A/C apparently has a leak in the coil or something and the previous owner had that part of the A/C sealed off. If it hasn't been updated to R134 yet, I'm going to have to upgrade soon I'm afraid. IMO, I think that R12 is most probably a better refridgerant, simply because it seems like old cars that still have the A/C working have ice cold A/Cs that get cold in <10 seconds (I know my 91 does). Bit. <10 seconds compared to maybe 25-30 seconds really isn't such a huge difference to try to keep it at R12 at all costs. just my 2 cents...

**GaryL** · 03-14-2007, 03:42 PM

I converted my dad's 89 Suburban to 134 a couple of years back and it still works great to this day.

On a side note, I was at Sam's wholesale the other day and they are selling cases (12 cans per case) of 134 for $36, that $3 per can. It's $10 per can at the parts stores. I bought a case just to keep on hand.

**collinsperformance** · 03-14-2007, 08:00 PM

i do dnot see any oil or wet spots at any of the connections but i see alot of cracks on the ac lines near the heat distibrution block. what is need to goto R134A? if i get the new hoses to replace the cracked ones what els would be needed? do i have to change anything on the rear system as well?mike

**TrailLeadr** · 03-14-2007, 08:44 PM

The system needs to be flushed, and cleaned. The condenser needs to be replaced. I forget if the compressor gets changed or not. The R12 oil, and R134 oils aren't the same, and don't play nice together.
I wouldn't suggest performing the conversion yourself if you're not familiar with AC systems. However if you really want to do it, I'm sure that some of our members would be able to walk you through it.'