Alright the low down first....

1) New Compressor
2) New Acumulator (dryer)
3) New Expansion Valve

Alright I'm using a hydrocarbon refrigerant, NOT freeze 12. The name of the product is ES-12a , and it gets cold!! 100* day, and I had ~58* air from the a/c.

The Problem...

The compressor is fine at idle, but under throttle it's starts to cycle. This is causing the power (hp) to come in and out. The duty cycle is about 5-10secs, then switches to off/or on. On the low pressure gauge, it kicks off at 25psi, and kicks back on at 45psi.

The Question...

Is this normal? Should it cycle in and out that quickly? I set it on "max" when I am testing it out. This means that it should stay on the whole time.

The Weather and Time...
9:30pm, 84*, 56%.

thanks guys

 

Alright , I did some research and found out that the expansion valve is stopped up. I cleaned it out, but I guess I didn't get everything. Does anyone know the part number for this peice? I can't get my shrader valve core out, so I would rather find the tool to do this.

 

Add more freon. I fill them so it holds around 40 psi constant at idle. Yours is kicking in and out because it's low.

 

Hmm.. . Interesting, but I know that I have more than enough in the system. One can of ES-12a is equal to 18oz of r-12. I used three cans, which would technically be overcharge. This last time I used a litte more than 2.5 cans. This would be equal to 48oz, which I have read is what the f-body system takes. I have enough in the system, it just doesn't want to work.

I have a lot of condensation on the acumulator, normal, but I also have some on the lines at the rear of the compressor. When condensation is on the lines, that are directly bolted to the compresser, this means a problem with the expansion valve.

 

25 psi is too low. There's not enough refrigerant in the system.

The low side shouldn't go below 40 psi on a 100° day, at any engine speed.

Ignore what you think you've read. Read the gauges instead. They will tell you when you get it right.

Condensation is normal. All of the parts of the system between the orifice tube and the conpressor should be below ambient temp and therefore may sweat given the right conditions (high ambient humidity). This does not indicate a defect. If you read that in the same place you read the other, you need a new source of A/C info.

Sounds to me like your system is working fine, you just need to finish charging it.

 

And after all that just keep in mind that the compressor "on" time will be less with the motor revved up than at idle. Takes less time to work the pressure up with the compressor running at 3000 RPMs than ti does at 1000 RPMs. Then it shuts off and the pressure bleeds down again, but at pretty much the same rate regardless of what RPMs the engine is turning. At idle it can run continuously on a hot day but when revved up it will often run for only a few seconds and then shut off again for a while, cycling on and off.

 

Thanks, except no. The new expansion valves was clogged with some small particles, causing the pressure to variate. Got it fixed now.

 

You consider 58* on a 100* cold?

Mine blows low 40s on a 90* day and mid 40s at 98* + high humidity. And that's with R134A.

 

with autofrost(r-12 replacement), which i highly recommend, blows out 38* on a 100* day on the road. this stuff is great. i hate south texas weather.

 

Nice! Now that I call cold!

 

Ther are a lot of factors that affect the air temperature coming out of the vents.
1.) Relative humidity- More humid air contains more water vaper and requires more heat transfer(latent heat) to condense the vapor into liquid water, resulting in a higher supply air temperature coming out of the vents. Total BTU's have not changed, but more energy goes into the latent portion than the sensible.
2.) Fan speed- The less amount of air flowing past the evaporator, the colder the air will be. BTU's have not changed, but since airflow is lower, change in temperature is higher.
3.) Road speed- More air moving past the condenser will remove more heat from the refrigerant and also make the supply air temperature colder. BTU's higher, airflow through evaporator stays the same, so change in temperature is greater.

58 degrees is actually pretty good for a supply air temperature with 55 being optimal. Any colder that that can become uncomfortable when the air is blowing directly on you.

If you are going to compare air conditioning supply air temperatures, then all of the conditions need to be equal, otherwise it is comparing apples and oranges.