Air conditioning

[CRM]

What is the brand name and part number of the new compressor? 3.2 lbs of R134a? That is a lot of freon. Is there a sticker in the engine compartment that confirms that?

 

[Trucksareforwork]

I would check the charge as well. 3.2 lbs sounds very high. I think I got maybe 36 oz (about 3 cans) or less (my memory is 2.5-ish cans) in my 85 305 A/C unit earlier this year when I repaired it (meaning I put a new delco compressor on it and changed over to R134a).

Edit: I may be off on my memory after looking at some of the capacity calculations I've referenced in the past, but I remember getting good pressures and cooling at less refrigerant than the "calculated" capacity.

 

[85K304SPD]

Show us your set up, so we can know what you are working with? What kind of compressor etc...

 

[fast 99]

Looked up the capacity, according to Mitchell that vehicle takes 3.25 lbs of R12 subtract 20% if using 134A that's 2.6.

 

[SirRobyn0]

The low side sucks right down to around 20 then the compressor cycles off and on I know that the book says 3.2 pounds but the high side keeps climbing and yes I'm charging through the low side

Also not answered previous question or I missed the answer, does the high side climb up that far right away, like within a second or two of operation. If yes it's almost certainly a clog. If it takes a little bit of operation like a minute or so and you can watch the gauge climbing then it's almost certainly air flow issue or over charge. Personally I doubt it's an over charge issue. I see what you posted @fast 99 and while he my very likely be over charging it a bit given the R-12 / R134A retrofit, I just can't see that alone being enough to cause a 350 high side.

 

[fast 99]

Also not answered previous question or I missed the answer, does the high side climb up that far right away, like within a second or two of operation. If yes it's almost certainly a clog. If it takes a little bit of operation like a minute or so and you can watch the gauge climbing, then it's almost certainly air flow issue or over charge. Personally I doubt it's an over charge issue. I see what you posted @fast 99 and while he my very likely be over charging it a bit given the R-12 / R134A retrofit, I just can't see that alone being enough to cause a 350 high side.

Agree 350 is quite high. There is something odd going on here that we don't know about. Could a gauge be defective? Don't know what the high side cut out is, 350 should be close.

 

[Wesley0620]

Not immediately the high side will start up when I start putting freon in and then the compressor will kick off and on but as I keep adding freon the high side will just keep climbing although the compressor will still cycle on and off although of course less frequently and I thought the same thing about the gauge but I borrowed another set from another mechanic and they show the same thing the system is completely stock Chevy setup with an R4 compressor and this system does not have high side cutout

 

[Bextreme04]

So, how much will it take before the high side is stabilized around 250? What does the low side read when that happens? What is the vent temp when that happens?

 

[Wesley0620]

It will go up to over 200 with 1 12 oz can but when I start adding the 2nd can it will keep going up and climb to 350 before I get the 2nd one half in

 

[Bextreme04]

It will go up to over 200 with 1 12 oz can but when I start adding the 2nd can it will keep going up and climb to 350 before I get the 2nd one half in

Soooo... have you never gotten it stabilized in the 200's? Vent temps? Low side pressure at that stabilized 200-250?

 

[Wesley0620]

Vent air is just ambient not cooling at all and low side is low enough that the compressor cycles but if I try to add enough to keep compressor on the high side goes higher and at that point I unplug the compressor

 

[85K304SPD]

Isn't the high side valve supposed to be closed when you are charging? I dont remember right off the top of my head.

 

[Bextreme04]

Isn't the high side valve supposed to be closed when you are charging? I dont remember right off the top of my head.

Yes, but it still reads on the gauge. You fill from the freon can through the low side port, but you will still see pressures from both ports.

 

[Bextreme04]

Vent air is just ambient not cooling at all and low side is low enough that the compressor cycles but if I try to add enough to keep compressor on the high side goes higher and at that point I unplug the compressor

Well, like I asked you earlier... do you see, or can you feel a temperature difference on either side of the orifice tube? Does it feel hot to the touch on the high side of the orifice tube? Is the return from the filter/dryer to the pump getting cold and getting condensation on it?

 

[Bextreme04]

Because at this point it sounds like there is either a problem with the orifice tube or you have a restriction somewhere else between the orifice tube and the compressor