Airconditioning question

[CAT Lover]

I had some major work done to my truck recently, new A/C condensor, high low lines replaced & a new dryer installed.

the AC works now, but still feels a little warm. It was about 80* today.

I put a simple guage on it like the one pictured in the link below & the PSI was about 7. Which seemed very low. I put the same guage on my Ford e350 van & it was at 30 pounds right in the middle of the green safe area.

I'm not an expert on A/C & was curious if this low reading was somthing that was normal for the CAT 3126? I do have ice forming on one of the lines that run along the firewall under my dashboard.


Reading Car AC Gauges - Bing Images

[fletch460]

Cat, not an expert by any means but ice forming is a sign of low charge. In my last MH I had to add a can every 4-6 mons. You need the pressure higher into the mid 40's I believe. Dont think it makes a difference if diesel or gas. Could be wrong. There are some AC guys on here.

[slemnah]

Was the compressor turning? 7 psi on the low side means you are very low on freon. You have a leak somewhere.

[calhyatt]

Originally Posted by CAT Lover

I had some major work done to my truck recently, new A/C condensor, high low lines replaced & a new dryer installed.

the AC works now, but still feels a little warm. It was about 80* today.

I put a simple guage on it like the one pictured in the link below & the PSI was about 7. Which seemed very low. I put the same guage on my Ford e350 van & it was at 30 pounds right in the middle of the green safe area.

I'm not an expert on A/C & was curious if this low reading was somthing that was normal for the CAT 3126? I do have ice forming on one of the lines that run along the firewall under my dashboard.


Reading Car AC Gauges - Bing Images

R-134A system would run a low side pressure higher than that. Ice forming on the line indicates that the pressure is too low in the system. I would carefully add 134A using eye protection until you reach a higher pressure between 20-30 running engine at 1500 and blower on HIGH. I have had to add about 6 oz. of 134A to my system once a year to maintain the pressure in the green arc. Hope this helps.

[CAT Lover]

Since we hit the 90's the past couple of days I added a little more freon. I'm still not near that green area on the guage. But the cab is cool & comfortable so i'm not going to push it anymore right now.

[Ranger Smith]

I think I had to put in like 7 cans when I purchased our current rig. They replaced bad compressor before we bought it and NEVER charged system. They didn't want to pay the extra $$$$. Now ours is at the proper pressure for the temperature. I sucked ours down with a vacuum pump before charging.

[CAT Lover]

Originally Posted by Ranger Smith

I think I had to put in like 7 cans when I purchased our current rig. They replaced bad compressor before we bought it and NEVER charged system. They didn't want to pay the extra $$$$. Now ours is at the proper pressure for the temperature. I sucked ours down with a vacuum pump before charging.

The mechanic evacuated & charged the system, he had too I had major parts replaced. Two lines, condensor & dryer. He did not put enough in. It's better than what it was. I'm worried that if i keep pushing it i'm gonna blow out the seals & lock up the system.

[CAT Lover]

Originally Posted by slemnah

Was the compressor turning? 7 psi on the low side means you are very low on freon. You have a leak somewhere.

No, no leak. The system had major work done & it was leak tested with dye. Since I got it back from the shop I haven't lost any freon.

[TXiceman]

When you are checking the refrigerant level, you need to have the blow on high speed and the temperature control set as low as it will go. Take the engine speed up to about 1000 to 1200 RPM and hold it steady there. Now charge the refrigerant in until you have the proper pressure.

And I have never trusted the dye leak tester. You need some one with a electronic refrigerant detector. These things can detect a leak of a few ounces per year. I'd take it back to the shop and have them finish the work and check for leaks properly.

Ken