Intermittent A/C

[lsupcar]

My a/c will sometimes work normally, but othertimes will experience a one to fifteen minutes delay, in which time, while on auto, no a/c'ed air will be blown, and then, when it starts working and blowing cold air, it might cut out for another minute or two before coming on again like normal.
I have searched and found others complaining of these symptoms, but no one has posted a cause that led to a resolution.
I've recently had a new compressor and drier installed and will likely take it back to the shop to be seen to again, as this was a problem that has been occuring for a year or so and the repair was only about two weeks ago, but I don't have time right now to bring it back in.
If someone has a solution to this problem I would appreciate the help.
Thanks.
Bill Z

[Manarius]

Sounds to me like a refrigerant charge issue. Either the refrigerant is undercharged (the most common case) or it is overcharged.

In the case of undercharging, the compressor will not turn unless the system senses enough refrigerant in the system. Perhaps your system is just on that edge and that's why it's going off.

Overcharging, well, it's going off because it's over-pressurized. A set of a/c gauges could probably help you figure this one out quick.

[92snowmachine]

is your ac r12 or r134a. if it's the new stuff you can buy a recharge hose kit that screws on top of the can and hook it to the low side to see what your pressure is from this reading you can figure what the high side is as well. they sell around here for about 10 bucks.

[alia176]

I'm bringing this to the top as my symptoms seem to match the original poster's. However, in my case, the HVAC diagnostic revealed code 14 & 15.

Code 14: evaporator sensor open
Code 15: Refrigerant temp sensor open

I'll check the two connectors on the evap box to make both are connected.

I converted the system to R134a and replaced every single component. The evaporator is about three years old along with a new expansion valve. The compressor is one year old and it's brand new. I did all the work and made sure all sensors are in their respective locations inside the evaporator housing.

Last year, I had an a/c shop recharge the system with R134a and she ran very nicely. This year, I'm having the symptoms described on post #1.

Anyway, I'll report back with my findings. Refrigerant charge is good, maybe a tad too high. I did manage to put in a can of R134a and maybe I shouldn't have. The low side pressure was a tad low for the ambient temp so I sucked in a can. In retrospect, I should've resolved the diagnostic codes before introducing this variable.

Thanks for any inputs.

[92snowmachine]

what pressure where you at and what was the ambient temp?

[SpecialFX]

I have the same issues. It works 90% of the time, but sometimes does the same as the OP. My car is a big question mark though as I've had it less than a month. I'm interested in seeing if anyone figures this out!

[alia176]

Originally Posted by 92snowmachine

what pressure where you at and what was the ambient temp?

Good question and this is where it gets dicey.

When the system refused to turn on last month, the low and high pressures were about 120 psi with ambient temp around 75°. The comp wouldn't run on this particular day.

Two days ago, the same thing happened and I watched the comp while the gauge was hooked up to the low press side. I used the cheapo gauge that comes with the can. This is more portable and easy to use when I want to do a quick check, while I'm running around doing errands, to see what's going on. The low pressure was 130, ambient at 80°. The comp would cycle on for about ten seconds and the pressure would drop to approx 40, and then shut off and pressure return to 130.

Yesterday, ambient temp was around 82°, the a/c system ran perfectly all the way home. No issues what so ever Vent temp was at 60°.

According to this linkie, high pressure at the low side could be one of three things:

- Expansion valve opened too wide (mine is less than five years old)
-Heat sensitizing tube faulty contact (this could happen, I suppose)
-Too much refrigerant ( I did add a can of r134a last month)

Attached is a pic of my evaporator before re-installation.

I'll take my manifold gauge to work today and hook it up at lunch to see what's going on and report back with more concrete numbers.

Thanks

[Conn SVX]

Anyone have a leak? How did you fix it. Icingdeath suggested o rings . Anyone else have success with that? How many people have replaced compressors? Are they known to fail often?

[92snowmachine]

mine was low when i got the car so i sucked it out replaced all the o-rings and receiver/drier (which you do any time you open the system) and it's held a charge for several years now. compressors aren't really likely to fail unless they are not run enough or run when the refrigerant level is too low.

[torxxx]

I am currently having issues just like you are with the AC. There is a way to bypass the safety shut off for overpress/underpressure. You unplug the compressor wire and either power it or ground it, (cant remember I did that last summer) but it will turn the clutch for the AC pump on so you can run the system.

Wiggle any hose connection on the AC system. This is how I found my leaky O-rings. Even though the bolts were tight on the highside pressure line to the pump, the oring would leak if any side pressure occured on the fitting (so when I would hit the gas, the engine TQ would move everything enough that the oring would start leaking.

They sell Dye kits for AC, sometimes thats the only way to find small leaks in the systems.

[Conn SVX]

http://www.autozone.com/autozone/acc...questid=136530
Is this the kit? Still would like to know location of these 0 rings!

[redlightningsvx]

theres 2 on the compressor where the low and high temp hoses connect, one on the driverside of the condensor, and 2 on the dryer beside the ABS.