As anyone ran into a similar problem....
My a/c clutch comes on for 2 seconds and then cuts off for 2-3 seconds and then comes on again and so on. When I put a gauge on the low side I watched the pressure build to about 60 psi and then the clutch would click off. I haven't put any freon in, so I'm assuming something is blocking the flow of refrigerant. Any ideas b/c its 95 in New Orleans and I'm dying driving to work and home.

 

I had a similar problem on a different car. I had the system flushed and added more freon and it started working.

 

Receiver Dryer or Pitot tube clogged.

 

Go ahead and put freon in and it will stop cycling like that

 

Contacts in the low pressure switch close at 50 psi enabling the clutch. For R134, they reopen at 22.5 psi and ground is removed so the clutch is disengaged. If the low side is going to 60 psi and the clutch is disengaging, you need to see what the high side is doing - it will open at 430 psi and if it's getting that high, it's seriously plugged up. I wouldn't add anything to it until you know.

 

I have the exact problem! I posted a message, and was hoping to find an answer.

 

i'm having the same problem with my 95 chevy truck - i was contemplating replacing the entire system -
minimal costs for the truck - i think around $600 or so - for parts (again for my truck) that included evap, compressor, condensor and a couple other parts that i can't remember right now.

 

I didn't like this answer I got from Chevy service on a previous new Camaro and Blazer, I complained about the same thing they said to increase the temp and increase the fan speed.

When my vette idles it cycles a lot and its been recently serviced, I'm not sure of the interval though. Long story short, I tried this and daym'd if it don't work. I just boost the fan speed up to see what happens and it cycles on and stays there.

You might try it just to see if it causes a different behavior.

 

I just did the retro to 134 and the system was in a vaccum, I dumped 1 whole can in before the clutch started doing as you described, by the time the next can was 1/2 in it stopped ccyling and operates as "normal" then I stop charging once the low side stabilized at 43 lbs.

You really need to put a set of gauges on there, otherwise you could cost yourself more $.

 

I agree with Cajun. Orifice tube or dryer (filter) could be clogged. I'd change both to be on the same side before adding new refrigerant. Cheap insurance.

 

Sorry for the untimely response, I just moved recently and was buried in boxes while I unpacked and started a new job...

Is the orifice tube inside the evaporator housing box, or is it inline with the a/c tubing in the engine bay? The accumulator seems easy enough to change. What tools do I need to purge the system and put new refrigerant in, or can I just change these two items and add some R134a after? I'm not to hip on letting refrigerant escape into the atmosphere.

 

Where ya' at? Tholm

Fellow New Orleanian here--actually live in Gretna-Just across the river.
I know exactly what you mean about the heat--it was 85 degrees at 6:30 am this morning before the sun was up.

Plan on spending at least $175 for evacuation and recharge by a shop. I just went through it because of a leaking High pressure schrader valve. Whatever happened to the $19.95 AC service?

Steve

 

The compressor does this when it is low on gas. Put a guage on the system and see if it is low. There are kits for sale that are complete with gas, leak detection die and pressure guages. Check out any good speed shop/parts store.

 

Nola-

I live uptown on Dante Street. You're right about the heat, I just got to work and I'm sweating in my office. Where did you get the work done? I'm not originally from N.O and I have a hard time trusting shops around here. I was taking my car to Corvette's unlimited out by Zephyr’s field, but I knew more than he knew, I just don't have a garage to do any work in.

 

When I put a gauge on it, the low side flew up to 60 psi in a second or two, so I think my orifice is clogged. It was blowing perfectly fine until one day the safety pressure switch started cutting the clutch out on me. I just got a manifold gauge yestersday and haven't read the high side yet.

 

I was actually on a road trip in Georgia when AC died on me on last Saturday. Went to a Meineke shop-all I could find--and they evacuated, check for leakage (found none) and recharged. Worked great for 1 day then died again. Went back to the same shop and mechanic said it was a leaking schrader valve (high side). He then proceded to destroy the valve core (twisted it off)trying to remove it to replace it. At that point the manager says "sorry" we're not responsible. $147 and I leave with a car in worse shape than when I drove into the place. The mechanic couldn't even remove the valve fitting because he used a hex socket when an octagon socket is need so he rounded off the alumunum fitting. Drove home from North Georgia Monday with no AC--Miserable!!
I did have a warranty though and brought it to a Meineke shop on Elmwood Pk blvd right next to the Elmwood Palace theatre. I bought the replacement valve fitting at Leson Chevrolet for $7.56 and gave it to them to install. The owner/manager there had a really bad attitude, first because it was a warranty job and then because I had a Corvette. I asked why --He said Vettes are hard to work on. I told him the whole front end comes off when you open the hood- it should be easier to work on than a car with a regular hood. That was yesterday and so far so good.
Bottom line after a long story--I can't be much help as far as mechanics you can trust in the area. You may have noticed even if you've only been here a short time--the education level is embarrassingly low. Smart mechanics are almost impossible to find.
I just got my Vette in May and have done all of the maintenance myself. Except for the AC --just not cost efficient enough to buy AC repair equipment.

Steve

 

NOLA-

I've been here for 5 years, I know what you mean. I went to a goodyear on Airline in Metairie for an alignment and to check the a/c out. I walked next door for lunch and when I came back they told me they couldn't work on it because it was a corvette-alignment too complicated and it had climate control. Instead of telling him its not the climate control, but a high pressure situation, I just left. I went to sears to get my car aligned, it's worse than it was and the steering wheel isn't straight. I think I'll just call around and see who can flush and evacuate the system for me. Harbor freight sells a $16 dollar vacuum pump for R134a a/c systems. I have no idea if it will work, but I can leave it on for a really long time. It says its 4.2 cfm, which I understand to be OK. I already have a huge can of R134a, so maybe I can charge it back up myself.

 

That vacuum pump at Harbor Freight caught my attention so I checked it out--It works with an existing air compressor--I was curious as to why it's so cheap.

Steve

 

Because it's not really a pump, it's just a siphon. The air from the compressor is forced through a venturi to accelerate it, and then past an orifice in the side of the pipe, creating a vacuum in the orifice. It has no moving parts, and the box it's in is just to give you something to grab onto and store it in. They work pretty well, but not as well as an electric powered pump. It won't pull quite as low a vacuum, its noisy, and it will really run your compressor hard if you don't have a big one.

 

I used one of those cheap vacuum pumps on my a/c, worked pretty good. I think it took me around 10 minutes to get vacuum around 25 inches, i have a 4 HP compressor. You need a set of gauges that will register vacuum. If you don't pull a good vacuum it is hard to refill r-135 or whatever. I agree with several other people, cycling means low freon.