A/C Issues

[Rex2nr]

I bought my truck (99 4.0) last summer and the ac wasn't working. I wasn't too concerned until this summer and I am sick of driving to and from work in a puddle of sweat. I added r134a-about 12 ounces- along with some pag 46, 3 oz. the compressor is kicking on, but immediately kicks back off, and repeats this cycle. It only stays on a couple seconds and is off maybe 10 seconds. I have one of those auto store refill kits with the gauge built in. The gauge shows pressure building until the compressor kicks off and then it drops again.

Should I keep adding r134 or is something broken? I would lean towards a pressure switch if the system is full. How do you check them?

 

[RonD]

If system was 0 psi for more than a month or two then you need to replace Accumulator/Drier, it is not expensive.

So did the system have pressure before you added refrigerant?
If it didn't then there is a leak somewhere so make sure any refrigerant you add is colored, green or red, so you can spot a leak.

Pressure switches do fail but it isn't a common problem.

You need to get/rent/borrow an AC gauge set.

Since the compressor does start the 2 pressure switches are "working", but one could be opening, cutting power to compressor, when it shouldn't, but no safe way to tell if that is happening without the pressure gauges hooked up.
I.E. if you have a blockage on the High Pressure side and "Jump" that switch you could end up blowing out expensive parts like the condenser.

Pressure gauge can also show if there is a leak.

How AC works picture here: http://www.movacs.com/How it works/acsystem.jpg

Compressor makes refrigerant High Pressure, it goes thru the system until pressure is relieved at the expansion valve, this expansion(lowering of pressure) is what makes Evaporator Cold, then the now low pressure refrigerant goes back to compressor to be re-pressurized again.

So not much to it, your home AC, refrigerator and freeze work the same way, compress and expand(release pressure).

First check pressures, if compressor comes on and high side spikes too high then something is blocked, or if compressor kicks on and low pressure drops then maybe not enough refrigerant.
Really no pat answer.

Good read here: http://aircondition.com/tech/questions/82/Troubleshooting-with-Gauges-FAQ

 

[97RangerXLT]

^^^this.

A compressor will cycle frequently if it is low on refrigerant as well. Do get the manifold gauge set and see where things are. My guess is you still need refrigerant but you definitely want to rule out any other issues. My 97 takes 25 oz and 7 oz of PAG oil. There should be a sticker on the radiator support that tells you how much you need.

AJ

Sent from my Samsung Galaxy Note 4 while sitting in my underwear

 

[Rex2nr]

I put 6 oz of R134 with the stop leak and dye in, and got about half a can of regular in. I'll see what I can do to find gauges.

I have no clue on where the pressure was at before, just that the compressor would not turn on. R134 was cheap enough at Walmart that I could just fill it and see what happens.

I also have read through the article in the tech section about 3 times, but should read it at least 3 more to fully digest!

 

[Denisefwd93]

there are too many variables in automotive ac systems. even people in the HVAC biz get confused.

Basically if you don't know what you had or don't have in refrigerant (and oil) You don't know what you need! best way is always to do a weighed in charge per specs. trying to read gauges without knowing what they should read is also futile.