Truck has sat since March, and the AC wasn't used for a few months prior to that, so now that i've got it going again the AC wasn't cold anymore. So put my gauges on and at 70F ambient I had ~20psi low and ~150psi high, and the sight glass had a bunch of bubbles. So I added some refrigerant and got it up to ~25psi low and ~200 high, at a high idle, with about 45deg output temp. The output temp may have gotten lower if I would have let it operate longer.

So my question is, how are my pressures? Is 25psi low and 200psi high good, at 70F ambient? Oh and also the sight glass still isn't clear.

Thanks, Aaron

 

Doesn't it depend on which refrigerant you are using?

 

There are many factors, not the least of which is the relative humidity and dew point. Put a thermometer in a vent and watch the sight glass and stop filling just before it clears up. I live in Phoenix AZ and this is kind of important ,A warm to hot, dry day is the best time to time charge ac systems...Hope this helps...Mark

 

Do you have a fan blowing air into the condenser?

 

Are your pressures with the engine idling or reved up?? I would go with R12 till the bubbles just dissapear.
Your suspose to run it for about 15 minutes first for the system to stabalize.

 

Just the stock fan pulling air, I didn't have a box fan at the time, so that may have been an issue.

Pressures are with engine revved to above idle, 1000-1100 rpms, and didn't let it stabalize for 15min, so that could be an issue.

Also located here in denver, so the humidity is never too much, just a guess maybe 15%.

So what should be the maximum low and high psi, if I have a fan blowing air through condenser, and run the system for 15min?

Thanks, Aaron

 

There really is no correct answer to that. All those conditions affect the pressure. Do a search on AC, as all of it is the same whether on a vehicle or a structure, you will find charts with the "range" of acceptable pressures for any given atmospheric condition. I don't recall exactly, but I seem to remember something about a maximum temp drop of 30 degrees from ambient air temp. Did you put a thermometer in a vent. Also, many systems have a filter/drier or accumulator filter in them that, when they clog, play havoc on the pressures. I do not know if this system has one, maybe a wiser member can chime in. good luck...Mark

 

We do have a drier in the system. It's the drier that has the sight glass on it.

Without the fans blowing on the condenser, you're not going to get the dash vent temps down. What are you vent temps while driving around at 35+mph?