Yeah, but how do I change it if I can't even see the damn thing?

 

Don't worry about the low pressure switch for now. Add refrigerant and see how it does. I've never seen a faulty pressure switch cause rapid cycling, either they work or they don't.

 

Okay, I'll try that. Now I need to tell you that I am a bit nervous about adding refrigerant mainly because that guage on the refill kit read that it was full. I know you said those guages can be inaccurate. I just don't want to blow up my system.

 

If it overfills for whatever reason, the high pressure pop off valve on the manifold line by the compressor will open before anything really bad happens.

 

Well, that should sound like a center fire pistol round going off!

 

I agree. I had this happen once and nothing bad happened.

 

You haven't lived until you've gotten in a hurry on an A/C job and start disconnecting lines without recovering all of the refrigerant.

Ask me how I know...

 

Hi, just joined. I have '01 and mine is doing the same thing. My check engine light came on first, then A/C not working right...not cooling enough, short-cycling. I did find out that if you have a digital odometer, hold trip button in while starting engine and codes will be displayed on odometer, I just haven't been able to decipher codes. Hope this helps, ya'll have help me.

 

I just did my 97 today. I added one full 8oz can, which helped a bit, but it's still not quite cold enough, so I might add a second. I was worried about blowing myself up, doing it on the high pressure port by accident, luckily I guessed the low pressure! I wasnt sure if adding a second can would be too much, I don't have a gauge? Guess I'll find out tomorrow.

 

Okay guys, here's a play-by play...............
Hooked up fill hose without can to low pressure port.
Started engine and turned on max A/C with windows open.
Checked gage reading. Reading was going down when compressor would cycle.
Compressor was short-cycling 4-5 seconds on-off.
hooked up can of r134a to fill hose.
Opened fill valve. Compressor was sucking it in and immediately stopped short cycling. Continued to let it suck in the refrigerant for a while. gage still reads in the blue, but towards the high side. I'm not sure if it took the whole can or not, but the can feels lighter. (Yes, it's still attached to the hose.)
Ambient temp here is 68 deg f.
Went in the house and got my indoor-outdoor thermometer. Got in the truck, closed the windows, stuck the probe in the dash vent and just sat there. Looking......staring...........
Fan was on the hurricane setting. Vent temps were reading 45 deg f.
Slowed the fan down to a bit less than half speed.
Vent temps stabilized between 44.7 deg-45.2 deg.
Is it good??????
Am I done, or should I put more in?
Did I dood it?????

 

Sounds good to me. Ride down the highway and get some air flowing across the condenser and see if the temps drop any further.

 

Thanks Quintin, I'll do that.
I'll let you know.

 

Okay, took it for a drive, went to the store.
Didn't have my thermometer with me, but the air at the vents "felt" colder than what I felt when it was idling in the driveway after I filled it. I should have taken the thermometer with me instead of relying on my calibrated "finger thermometer".
Yes, the air blowing did feel colder. Although I must say, it didn't have that cold "bite" I was looking for. Maybe I'm expecting too much and thinking it should be as cold as an r12 system.
In the back of my mind, I'm sure the system is full. First impulse though is to say....."Add more r134a!" because it got cold when I added it.
What do you all think?
Quintin, what do you think?? You've been a good help to me.

 

Nah, about 40-50 degrees at the vents is good. Any colder than that and the system might start freezing up. I wouldn't recommend adding another can of 134a, since we never knew how much was in the system from the start; better to undercharge slightly than overcharge. Yes, R12 systems do run slightly colder, but I don't think it's enough of a practical difference to know. I've seen 134a systems that literally threw bits of ice out the vents riding down the road. Thing to remember when comparing R12 and R134a is not vent temperature between the two, but vent temperature period. Regardless of what's in the system, anything below 50 degrees inside the cab is gonna feel pretty durn good on a hot day.

Yeah, I think dood good.

 

Thanks Quintin!