A/C Compressor Clutch Plate?

[mankypro]

I've never worked on an automotive ac before and I'm about to recharge the compressor on my f-250 which only blows warm air at the moment.

With the engine at idle and turning on the ac the clutch plate on the front of the compressor kicks on and off for about 5 second intervals - I assume it's trying to reach operating pressure?

Weird, I tossed the gauge I have on it and with the compressor off it reads 0 then with the a/c on it fluctuates between 25 and 45 psi based on the clutch plate being activated or not.

Which reading do I assume is correct the 45psi or the 25? Don't particularly want to overcharge the system.

It was converted to 134 before I owned it. I assume the clutch kicking on and off is normal?

 

[mankypro]

The clutch just kicks on and off the air entering the cab is nominally cooler than outside air. I topped off the system with some 134 and still nada. Bad compressor?

 

[funnyman06]

I believe that when it kicks on and off like that the system is very low but not empty, on my truck the clutch kicks on and stays on. But mine still blows warm, kinda sucks. Im going to assume the guage you used your installed it on the high side and not the low side. When you get the refill kit it will come with a gauge with safe levels and will say install on the low side.

 

[tractorman86]

where are you putting the guage? what is the pressure now that you put some freon in her. if you are hooked into the hi-side 45 is way too low if you are on the lo-side 45 is too high so make sure you are using the right port. also if you try to charge it into the hi-side you can blow up the can, so BE CAREFULL!!!

 

[mankypro]

I'm on the low side and yes it reads 25-45 with the engine at idle with the clutch going on and off. The kit I have only has a qd for the low side. The gauge reads right at the edge of full - not in the warning zone.

With the engine off the gauge reads 100psi connected to the can - weird. And to think I was a commercial a/c apprentice as a teen - you'd think I could figger this out. methinks meinike will be 99.99 richer by the end of the day.

 

[RLDSL]

I'm on the low side and yes it reads 25-45 with the engine at idle with the clutch going on and off. The kit I have only has a qd for the low side. The gauge reads right at the edge of full - not in the warning zone.

With the engine off the gauge reads 100psi connected to the can - weird. And to think I was a commercial a/c apprentice as a teen - you'd think I could figger this out. methinks meinike will be 99.99 richer by the end of the day.

It's starting to sound like you possibly have an overcharge. It's normal for the pressure to fluctuate, but to get up to 45 it would need to be mighty hot outside and would not normally get back down to clutch cutout point when it's that hot out. There's something bad out of whack here. What was the temperature outside when you were getting 100 psi static pressure in the system?

 

[icanfixall]

What may be wrong is the pressure switch found on the dryer is going bad but.... You probably do need to take it in and have someone thats trained to find and correct problems take a look at it. Also that clutch has a setting on it. Sometimes they wear out and need to have shims installed to close up the gap. I have seen the clutch plate break before and that causes all kinds of vibration hell.

 

[tractorman86]

What was the temperature outside when you were getting 100 psi static pressure in the system?

he said when he shuts it off, the pressure will equalize anytime the a/c is shut off. i'd bet if you had a real manifold set of guages the hi-side would read about the same when you shut it off. try putting a wire in the plug to your low pressure switch(the one connected to the reciever drier) loop it so you get a constant current to the clutch, dont leave it like that, just for a temperary test. a good SET of guages is really the only way to do a good job. without knowing the head pressure you are just going to be taking a stab in the dark.

 

[mankypro]

My local garage says I'm 2.5lbs low on freon and that they flushed the system and put fresh lubed stuff in and it blows as cold as ever...

They say there's probably a slow leak somewhere but they cannot find it.

 

[tractorman86]

these systems only take like 3lbs in the first place! get a spray bottle with soapy water(dawn dish soap mixed pretty rich) and spray down, while watching for bubbles, all over the condensor, then all the fittings on the lines then with the truck off the front of the compressor if possible

 

[Mr_Roboto]

Those kits in the stores should be illegal. They market to the public chemicals and procedures that should only be handled by a professional with the proper equipment.

Funny thing is for a shop to do A/C work they must have a recovery machine. But it's fine for the public to use the micky mouse stuff.

Now that I have a "real" A/C machine that can fill by weight (after evac), I can fix systems that I couldn't before trying to work off of pressures.