I just dumped a bottle of r134a into my truck. I have not done a pressure test on my current level, but the bottle gauge said it was full. Now my ac clutch cycles on for about five seconds, then off for 15. Inside the vehicle, the air blowing out is ambient temp, no cold. Before I added the freon my ac clutch was stationary, so the freon did something, but obviously not enough.

 

That sounds like what mine would do as the compressor was on its last legs. I'd have to keep putting refrigerant in it until it would work but it finally couldn't hold a charge. I found that directly under the compressor there was oil accumulating from where it was leaking on the underside of the compressor. I'll be ordering my parts for an AC rebuild this evening.

 

Upon further inspection, I rehooked the bottle and found the pressure being shown on the gauge would be high when the clutch was stationary, but would then drop when it engaged. Was the freon only going into the reservoir when the clutch was engaged?

 

Best look at the direction for the recharge kit. That said, you might be correct.

 

The way the air conditioning refrigerant circuit works is that the compressor creates a high pressure gas then the condenser coils turns it into a high pressure liquid. The high pressure liquid passes through the metering device which in this case is a fixed orifice tube. The resultant pressure drop creates a cold low pressure gas which passes through the evaporator coil in the cabin. The resulting low pressure warmer gas heads back to the compressor to start the cycle again. When the compressor stops, the pressure starts equalizing through the metering device until the high and low side are the same. During this equalization, the high side pressure drops and the low side pressure goes up until they are the same and appropriate for the ambient temperature. Freon is the registered trade name for R12 or R22 although it has become the "Kleenex" of refrigerants with lots of opportunity for arguments. Whatever you do don't put R22/freon in your system. Your trucks hvac system uses 134a.

George

 

Dunno what prices for R134a You got right now, but here, in EU they just surged last months. From about $7 per kilo to above $65.
I am waiting for my AC compressor delivery (old one kicked the bucket) and prior I fill in anything, I'll do a vacuum into the system for a week or so, to see if it's seal. Otherwise I may literally evaporate a hundred bucks :P
If You have a chance, collect the gas back to the bottle and do a vacuum/flow check using gauges. The principles of (hooked gauges) operation are in GeorgeLG post.
Cheers,
Mike

 

 

You just remind me I had to take an empty nitrogen bottle to refill. Sure I meant, the vacuum first, then a nitrogen charge. You can't observe the gauges behavior without a nitrogen. Neither if the system is blocked.

 

Nitrogen first to check for leaks, the vacuum to remove non-condensates (moisture and air). Then charge.

George

 

The low side and high side service ports are a weak spot and will often leak. Changing the low side requires a new drier/accumulator (about $15), the high side service port is replaceable (about $5). The high side service port requires an 8 sided socket. However most just use pliers along with a wrench on the aluminum lines to remove/install. This does mess-up the sides of the service port, but only reason to remove it would be to replace it, so use pliers on it. Just be sure to have a wrench on the aluminum line side to avoid twisting the line, costly mistake!