The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

piecesparts · 06-21-2008, 10:41 PM

R-134 systems are finicky when operating. The fact that you are retrofitting is giving you a system that is not engineered to a set amount of freon. This means that you will have to PLAY with it. TOO much and the interior coil will frost over (this will be noted when the air flow in the cab reduces as you are driving down the road) whe you turn the A/C off for a shor tperiod and then back on, air flow returns, the coil has defrosted. The short cycling is due to a low freon charge and the pressure switch is switching the clutch on and off when the pressure increases or decreases below it's setting. The amount of R-12 in your old system will be abut twice the R-134 you will need in the same size system. You may have to let it all out and start over to know what you have.

06-21-2008, 10:41 PM	#4
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: a/c cycling when engin rpm are up R-134 systems are finicky when operating. The fact that you are retrofitting is giving you a system that is not engineered to a set amount of freon. This means that you will have to PLAY with it. TOO much and the interior coil will frost over (this will be noted when the air flow in the cab reduces as you are driving down the road) whe you turn the A/C off for a shor tperiod and then back on, air flow returns, the coil has defrosted. The short cycling is due to a low freon charge and the pressure switch is switching the clutch on and off when the pressure increases or decreases below it's setting. The amount of R-12 in your old system will be abut twice the R-134 you will need in the same size system. You may have to let it all out and start over to know what you have.