Toro A/C system

[Tuco]

Anyone ever work on the ac system?

I replaced the compressor, hoses, dryer, muffler and expansion valve. Had the poa valve rebuilt and flushed out and pressure tested the evaporator and condenser. So everything is basically new.

Vacuumed down the system for 3 hours and let it sit overnight and it held steady vacuum so I changed it with about 1 3/4 cans of 134A. The high pressure got up to 200 and the air blows just barely cool.

What am I doing wrong? Should the high side be that high? Maybe add more refrigerant?

[Loaded 68 W34]

Did you adjust the POA valve or have it adjusted to work with 134a pressures? Also, are you talking about 12 oz cans of 134a? if so, 2 cans is not nearly enough. The system would have have been filled with 4 - 4.5 pounds of r12 (should be a label on the compressor). That is 64 - 72 oz. Converting to 134a usually requires 70% or so of the original amount. That is about 50 oz. or just over four 12 oz cans of 134a. 200 psi sounds a bit low unless it was really cool out. There is a performance chart in the service manual that gives high and low side pressures based on ambient temp and relative humidity. I think the 134a should run a few psi lower than r12 which is why the POA valve needs re-calibrated to run the 134a. There are r12 substitute refrigerants you could try as well. Basically, I think you do not have enough 134a in your system. I had enough r12 to fill my system with when I finished my car.

[Tuco]

Thanks for your reply. Yes I was using 12oz cans so I guess I need over twice what I have. After looking at the chart in the book it looks like the high pressure should be around closer to 300. I’ll try adding some more refrigerant tomorrow.

The poa valve was rebuilt for 134a so that’s good.

Would the lack of refrigerant cause a problem with the compressor? I drove the car yesterday and after about 20 minuets I heard a strange noise and started smelling burning rubber so I switched the ac off. The sound and smell went away so I figured the clutch had locked up the compressor and the belt was burning. But this morning when I went out and started the car and switched on the ac everything was working fine again. Any ideas?

[Loaded 68 W34]

Running the system dry may hurt it, but running it half full should not have hurt it. Did you add fresh 134a compatible oil to the system? Running the old r12 oil with 134a can cause the oil to gel and hurt the system. Obviously, running no oil will hurt the system as well. You may also want to look at the clearance between the front of the compressor pulley and the compressor clutch. When the system is off, the two surfaces do not touch. I had the opposite problem of what you are describing after I charged my system. I was running the system, but when I turned it off after a bit of driving I started to smell burning rubber and smoke started to roll out from under the hood. It turns out the the clutch was a bit too close to the pulley. When not engaged, the two were rubbing on each other and got so hot that all of the rubber on the clutch had burned off. Luckily, I have a bunch of extra compressors laying around and once I installed a new front clutch (with enough clearance) I have had no problems.

[Loaded 68 W34]

You should also check the belt tension. The belt slipping on the pulley would certainly cause strange noises and a burning rubber smell.