AC not cooling /

[loveMy850]

Lee, I hope you are right that is what I'm thinking. I'm a little skidish doing this alone. I'm not real confident with the gauge thing.

[dj_v70]

When you read the 45 psi, we need to know whether the compressor was running or not. When the ac is on, the center of the front of the compressor clutch should be turning when the measurement was made. Is it? If so, your freon is fine.

If your freon is fine, you need to find out why your system is cycling off/on and hence the warm/cool air. It could be one of several things. If you tee in a volt meter to the compressor, you can determine if the problem is the clutch/compressor assembly or something else.

[loveMy850]

Will you guys tell me HOW to read my gauge when adding freon to the system w/out over filling. Lets say it 102 degrees outside. Oh with a small can of 134 freon. Thank you!

[loveMy850]

Will you tell me exactly how to read my gauge w/out over filling. Lets say it's 102 degrees outside. Thanks Man

[dj_v70]

BE VERY CAREFUL WITH FREON, IT CAN BURN YOUR EYEBALLS ETC! Wear google just in case...

Assuming you have can of freon with hose with gauge on it...
a) Connect hose to can of freon, don't open can of freon. Assuming you have new can, open valve on hose such that the needle is in the full up position (ie. won't poke through can) and then screw it on the can.
b) Connect other end of the hose to low pressure fill port with the engine off. Your car is older than mine, so, I can't tell you where fill port is off the top of my head.
c) Note pressure on gauge. This is the static system pressure with system off. This should be at least 70lbs or so, else you are likely very low on freon.
d) start engine and turn ac on full blast. Check pressure on gauge again. Did it change? If not, your ac is not cycling and the pressure numbers that we have been discussing in previous posts don't apply.
e) If pressure went down when engine first started and is at least 25, then you are NOT very low on freon.
f) I would expect that the pressure will vary between 2 numbers as your air from your vents is either cool or warm. The number from the chart that I linked to earlier is the lower of the 2 numbers.
g) If your numbers are greater than 25 and changing every few minutes, then problem is not your freon. Something else is wrong with your system.

[loveMy850]

Thanks 4lv70.

[Ozark Lee]

Actually the low pressure switch - the pressostat) cuts everything off at 28 psi (give or take a pound - manufacturing variance).

R-134A has a temp and pressure curve that runs very close to temperature and degrees F being equal within the range that is of concern. Below 32 degrees the evaporator will start to freeze the condensate and it will quit passing air. The number (compressor on) that you need to maintain is at least 28 for things to work and stabilize.

In a perfect world you weigh in the refrigerant to a completely evacuated system, then you know you are right. That said, it isn't really rocket science and close is good enough. If you were somehow able to get 4 cans of refrigerant in it would lead to problems but if you get it to a point where the clutch stays in and the gauge stays above 34 or so when you rev the engine you are in reasonably good shape. I have never had a Volvo (Zexel or Sanden) compressor go bad from an overcharge. Usually they fail mechanically at the clutch which really has nothing to do with the charge.

Just make sure the interior fan is blowing on high and the radiator fan is on while you do all of this or it will lead to false readings.

...Lee

[loveMy850]

Thanks Lee.. All you guys have been great. The freon is good. Its ok now but it still seems that real light cool in and out at times.. I'm really thinking it's the clutch. I'm going to do the breadtie, but I seen one where they use copper metal clips. Its so blasted hot I'm afraid the breadties might melt. I need to go 02. Gauge right! Thanks