A/c Help

[Scout3]

High Everyone,
Pretty new to this forum and want to say hi and thanks for the help you have given me. I bought a 1997 XLT from a friend of mine for my son about three weeks ago. It is hi mileage but it looks almost new. My friend is OCD about his stuff and takes extreme good care of everything. Anyway I bought it knowing the a/c did not work. He had already change just about everything except the evaporator. I found the blend door broken and just completed the door fix someone posted in the forum. That man that came up with that deserves a medal. That part works great now. Vacuumed down the system for about two hours and leak checked for an hour more, all looked good. I have a question on freon quantity for the 4.0 SOHC. The sticker on the hood says 1lb 14oz. I have a book that stated 1.38 lbs and I found a source on line that said 22 oz. I have a case of 12oz cans. I went ahead and started charging the system. It took two 12oz cans to get the compressor to stop cycling at idle and temps in car were still in the 80's. At 2000rpm it would cycle again. Added almost all of the third can ( estimate total 33oz seems like a lot) it does not cycle at 2000 rpm anymore and air temp will be 48 degrees. At idle temp creeps up to 58 degrees. At 2000 rpm High side is 275 and low is 30psi at idle about 700rpm high side is 250psi and low side is 50psi. Outside temp is about 90 degrees. I wonder about the temp creeping back up to 58 degrees at idle. Any a/c gurus out there that can give me some advice. Thanks.

Ed

 

[Scout3]

Anybody?

 

[95ExpLim]

Not an ac guru

The "rule of thumb" is the high side reading should be about 2.2 to 2.5 times ambient which would be 198 to 225.

Are your condenser fins straight and not plugged?

I would go with the freon amount on the under hood sticker. By that you'd be a few ounces overcharged and would give a bit higher readings.

Use a garden hose and spray a fine mist on the condenser while you are at 2000rpm. If there is a dramatic drop you may have an air flow problem with the condenser.

 

[safn1949]

Low side should be 30-35 psi,I have a lot more experience with R-12 then R-134 but my 94 has a leak and I recharge it to 30 psi and it works fine.

 

[mr2fix2it]

sound like you are either overcharged or have inadequate cooling your pressures are too high should be 30 and maybe 180 at idle check cooling fan or clutch

 

[mr2fix2it]

i have been putting 1 lb 14 oz in all these trucks and never had trouble I believe this is the amount for this truck so look at cooling

 

[Scout3]

Thanks everybody. I will take your advice. I think I may have overcharged by a couple of ounces. I am going to let it ride for a while to make sure I have no leaks. It is comfortable, just not quite as cold as I think it could be.

Ed

 

[eagles350]

If you had a dead empty system & didn't pull it down with a vacuum pump you might have some air in the system. Also r-134 is very temperamental with the amount of charge. a little over or under will effect the temps. When I recharge I get close to what the label under the hood says & start checking the accumulator. When it starts getting cold you know it's getting close.

Note gotta read more, I saw you did vacuum !

 

[nathan626]

i am having problems with my ac on my 97 xlt it is the 4.0. the air worked great when i got it about a month and half ago now the compressor wont kick on. it is not seized up. and i have a cheap gauge that came with r 134 recharge can. it says it was way overcharged so i emptied the system but it still wont cycle. any help would be greatly appreciated

 

[Scout3]

Nathan,
I am no expert so take this for what it is worth. When your A/C system gets low enough that it wont turn on or that it has not been turned on for a while the High and low side pressures will equalize. By this I mean your Hi side will bled over to your low side showing a high reading on the low side. ( Don't know if I am explaining this right so you can understand). To get it to read properly you have to force the compressor to turn on. Where you attach that can you will find a connector on a switch. That switch is your low pressure switch. Disconnect that plug and take an unpainted paper clip and stick it in the two plug holes that have wires in them in that plug. Your compressor should run now and you can add freon normally. If it does not run you have an electrical problem or a bad clutch on your compressor.

Ed