AC Troubleshooting Report 308

Hi,

Last year my A/C started blowing warm (after about three years of blowing cold). It was properly converted to R134a years ago.

After some troubleshooting today, here is what I found....

Some facts:
Ambient outside temp. approx 75 deg F
Compressor belt relatively new, correct tension.
Fuse okay

With A/C OFF, manifold gauge set attached:
LOW side 23 psi, HIGH side 25psi

With A/C ON:

LOW and HIGH side readings remained unchanged.
Sight glass appeared to be clear
The compressor did not sound like it was engaging (or it is hard to hear with engine on?),used stethoscope - no change in sound coming from compressor, idle also not affected. So, sounds like compressor not engaging.

I am wondering:

What should the low side should read with the A/C disengaged and engaged?
The GT4 manual states Low side should be 1-2 kg/cm2, which is approx. 14 - 28 psi with system running. If this is the case, my Low side pressure is normal.

My high side pressure does not increase due to compressor not enaging.

I am assuming 25 psi on the HIGH side is very low, even without A/C on? What should the HIGH side read without A/C on? - very high probability my low pressure cut-out switch is coming into play...

Before I do anything else, i.e., evacuate system/recharge, I wanted to bounce this off you guys.....

Curious to know what you guys think......

Thank You,

Anthony

low on freon!

the pressures without Comp. on should be near(close to) outside temp. on both sides.

....cool....thank you! I was thinking/hoping for that answer....I'll recharge.....


Thank You,

Anthony

Hi,

Okay here is what transpired and my NEW PROBLEM!

...well today I slowly started filling my system while monitoring with manifold gauges. The system did have some initial pressure (20psi on Low side) as indicated in my initial post, and the compressor was not engaging due to low refrigerant charge.

I added 134a from a can very slowly....the compressor kicked on and dash vent temp. started decreasing from approx. 80 deg F (temp outside) to about 70 degrees......the low side pressure was still not up to where is should be (it was about 28 psi, HIGH about 120 psi). Sight glass went from empty to steady stream of bubbles - so far so good....

BUT, I encountered a problem that was not as pronounced in other vehicles that I have charged with a can: The can would only empty half way, i.e. as refrigerant went into the system and the can lost pressure, the can's pressure became too low to sustain refrigerant flow (or flow very slowly). I kept the tap on the half-full can and sealed it - used another tap on a new can, refrigerant flowed again until can only half-empty - Low pressure then read 32 psi/high 150 psi - dash vent temp. about 60 deg - sight glass has stream of bubbles, but as expected, less than before.

Now, I have two cans I have to dispose of properly and I still need to put more in the a/c system. When I did other cars in the past, the cans seemed to almost completely empty when refrigerant was needed.

I did not heat the bottom of the cans, but maybe I should have.....any advice or experience with this problem?

Oh, by the way, last year when I purchased a 12oz can of R134, it was less than $4. Now, the price (at every auto parts store I checked) is over $10 and rising! Seems r134 is heading towards the r12 route.....

Thanks,

Anthony