Charging AC

[jimeeh1]

In the process of re-charging my AC system after replacing the heater core in my 97Xlt 5.0 and wondering if anyone can answer a question or two. I've evacuated it and charged it with refrigerent and have it running. Its nice and cold, though the temp here in NE PA is 50, and the compressor cycles about every 10 seconds. The question is, the compressor cycles between 40 and 20 Lbs on the low side and I'm guessing cycles off with the LP switch. This being said, is there any way to determine if the system is under/over charged by pressure reading (I do not have a high side R-134a adapter for my standard manifold gauges) or is the only accurate way to tell by measuring the amount of refrigerent added? Anyone know the amount of refrigerent required for the vehicle?

Thanks,
Jim

 

[zhanx]

there is

but a few questions first (a/c guru for military stuff but hardly touch cilivain stuff)

The question is, the compressor cycles between 40 and 20 Lbs on the low side and I'm guessing cycles off with the LP switch?

ok first we need to know is the compressor clutch kicking out at 20 psi?

referring to my handy daney pressure chart it says at

. Its nice and cold, though the temp here in NE PA is 50,

it should be 45.5. of course you get some variance on that. say +- 5. under that is of course under charged over is over, but then again other things could be involved and throw off the readings

 

[dogfriend]

A/C Specs for 97

 

[dogfriend]

Additional Info including Torque Specs

 

[zhanx]

great info but i need more input for him on this to dianogise it (if it cycles at 20-22 its most likely a low charge but he never said how much him put in, got a few years at doin this)

 

[dogfriend]

I'm not that knowledgeable about A/C but I agree with you that he likely doesn't have enough charge and the low pressure switch is cutting out to protect the compressor.

 

[MalcolmV8]

Dogfriend, where did you get that program? Do you work for Ford? That looks super useful. Can we buy a copy LOL

 

[dogfriend]

Ebay is your friend. There is usually someone selling them on Ebay. The CD is for all Ford Trucks for a single model year (i.e. 1997 covers all Ford Trucks, even Aeromax for that year).

http://www.explorerforum.com/forums/showthread.php?t=56654&highlight=diy

 

[zhanx]

dido on your comments dogfriend (kind of) but as i said i need more info.. did you charge one can (16oz) or two..etc.. let me know and i can help

 

[zhanx]

what would better is input temp and output temp of the core etc.. but if wishes were horses we all could ride

 

[jimeeh1]

Looks like I should be good to go according to dogfriends attachment specs. Compressors is cycling around the "AC Cycling Switch" Specs of 47 PSI on and 22 PSI off and I have at least 30 oz. of refrigerent in system. If anything, I'm overcharged. I'm guessing the short cycle times are due to the cool ambient air temps.

Once again,
Thank You Dogfriend....You are truly a Explorer owner man's best friend.

 

[Glacier991]

FORD publishes a chart of compressor cycle times based on ambient and cabin air temps.... you have hit the nail on the head. In the ideal world charging by weight is the most idiot proof. If you are in the neverland of not knowing how much refrigenant you have in your system... vent temp checking is a good alternate method.... vent tamp method consists of stabilizing the interior temperature on... oh say a sunny 75 degree day... and then wait til the vent temps also stabilize. Run the engine at a constant 1500 rpm.... add a couple ounces of refrigerant, and see what your vent temps do.... if they drop, repeat... until they either do not drop or start to rise. That will be the "optimal" charge - at least for that day, those conditions, etc. But overall that is probably the best advice for anyone doing DIY and wanting to zero in on the correct charge. And your cycle rate sounds "about right" for 50 degrees ambient.

 

[jimeeh1]

Thanks for the follow up Glacier.