Hey guys sorry if this has been posted already but I just charged my ac system today and it reads 70 on low an 100 on high. The high pressure won't go up it still says needs service on the psi gauge. the low pressure seems to be fine when the compresser kicks on for 3 secs it goes to green. Does anybody know what the problem can be? Thanks in advance! I retrofitted it from r12 already.

 

Needs more refrigerant. Add another can and see what happens.

 

Is it okay for it to go into the redline pressure zone? (For the high pressure)

 

just add one can to the low pressure valve.if its still cycling add another can.

 

The compressor will typically cycle on at 45 psi or higher. And then cycle off at 25 psi. When it cycles off, the pressure builds back up to 45 psi and then the cycle repeats itself..... If the car is rapidly cycling while sitting in the driveway, it will be worse when you're driving down the street. The condenser will be getting more air (wind) blowing over it while driving. That just speeds up the heat removal, which thus makes the car cycle quicker.

100 psi on the high side is nothing. Our cars will sit at 250 psi during the summer months. Sometimes going as high as 300 psi. There is a high pressure cut out switch which activates at 420 psi. But even if you were up that high in pressure, you'd have very little cooling happening inside the car. The condenser would be absolutely swamped with heat. So much so that you'd be getting barely any cooling happening inside.

As long as your radiator fan(s) are running properly, they will keep the high side pressure in check. Now if you did actually put too much refrigerant in the car, this would result in too much high side pressure. But then you wouldn't be cycling rapidly either. It would never cycle off in that situation.

Cycling every 3 seconds is absolutely a case of low refrigerant. You're trying to compress a very small amount of refrigerant. This is easy to do. Hence why the pressure rapidly goes down to 25 psi and then shuts off. Once it hits 45 psi, it rapidly shoots back down to 25 psi......The trouble with rapid cycling is that you have a small amount of refrigerant to actually move the heat from the inside of your car to the outside. And it's hard on the compressor to have it cycle every 3 seconds.

High side pressure on a properly filled system under normal weather conditions will generally be in the 150-200 psi range.

 

I added another can and now the compressor doesn't stop cycling, but it does blow cold! it's running 45 and a little lower than 150

 

 

Depending on the ambient temp, it may still cycle even when full.

Wait til May... by then, you'll know for sure whether it's got enough in it yet or not.

 

Just make sure the can is upright when charging. It's better to get the gas than liquid on the low side. It takes a little longer and easier on the compressor.

 

nevermind, reread

 

Us cheap ol' geezers get the most possible freon GAS (i.e. upright )
by swirling the can around in a bucket of the hottest possible water.
It also speeds up the process a bit.

 

I have been going through a similar issue and read this post to help me with mine. It was good information and thought I would share what I have found out.

https://www.thirdgen.org/forums/cool...ml#post5564228

 

Don't even mess with the high side ports... Also after you change to R134, set the low pressure switch down to about 20PSI. I set mine to 18PSI.