A/C problem

[Rodd]

Okay I read through the 2 most recent posts on A/C. Here is what I have done thus far....

The A/C worked last summer and fall however the front didn't work great but worked and when I turned on rear with it, it worked great. Now to this year. The compressor doesn't kick on until I connect a can of 134 and then it only kicked on after about 10 seconds after connecting the can.

Filled it w/ 24 oz and it ran okay for a day then nothing. Put a can of sealer/dye and nothing w/ the glasses and black light. Today I put a 14 oz can of freon, sealer, oil, dye and it worked okay.

I bought the vacuum pump from HFT as well as the a/c guage set. Hooked them up and pressure was at 27. I disconnected the high pressure disco and air started coming out no freon. I put the quick connect back on and used the pump to purge the system and no freon came out just air.

It is stuck at -25 now and hasn't moved for an hour. According to the book since it doesn't change there is no leak. The high pressure connection on the truck has a little pin inside that I am assuming is stuck. What do I do next?

Thanks

 

[knkreb]

Just a friendly little tip for ya.... only add refrigerant. All that extra additive stuff isn't going to help, but more like hurt you in the long run. Refrigerant systems are closed loop. It doesn't burn oil like the engine does... and like over filling the crankcase, the same type of damage occurs with a compressor with extra refrigerant oil etc.

Suburbans... well best to check under pressure. Check the underside refrigerant lines leading to the back evaporator. Sometimes they crack, or rub and develop leaks.

The "air" you see is really refrigerant vapor. If you have air in the system, you've got problems.

 

[Pruittx2]

replace that high pressure switch,, then pull a vac again,,, if it holds,,, fill that dude with freon. The only problem with the H/F gauges,, is you'll need a can tap fitting,,to be able to use your gauges to put the freon in the system
http://shop.advanceautoparts.com/we...E4&srccode=cii_13736960&cpncode=24-87293149-2 like this

 

[Missy Good Wench]

The little pin you refered to is called a Schrader valve (very similar to a tires valve core but not the same materials)

If the core is leaking you will need to replace it. The complete High side quick coupler unit unscrews and is replaceable.

It should have a hex on it close to the line that will accept a wrench.

Be sure the system is at ZERO pressure when you unscrew that thing.

Since you have paid the $$$$$ for a vacuum pump and gauges. get a sniffer so you can snoop out any leaks.

As mentioned, all the extra goop, dye and such is a mess you dont need.

At this point I would flush the system out completely and start from scratch with the proper oil charge and the recommended 134 charge.

Snoop out those rear lines and see wasssup there too.

The dual systems can be a PITA to get going once they have quit.

The charge must be just right to work properly. The rear unit uses an expansion valve to modulate the flow of 134a through the rear core as opposed to the orifice tube up front. These valves can and do fail. The expansion valve is controlled internally by the thermostatic type diaphram and a little burbon tube that either penetrates the core or that is in contact with the oulet pipe.

This measures the temp of the core/oulet and allows the valve to control the flow of the refrigerant.


Missy

 

[Rodd]

Thanks guy's. The problem was the high pressure valve. Actually even though it a hex the top of the valve unscrews. It is like a bunch of little bumps around it just above the hex. I got the new part at AZ for about $7 w/ the low pressure shrader valve also. I suctioned it and It stayed at -25 for an hour with no leaks. Put in freon and all good.