A question about my '97 F150 4.6L AC. Compressor clutch cyles with 3 sec on and 3 sec off even with AC turned full on and fan full on, and it's hot here in Phoneix. High pressure and low pressure lines are quite hot and cold as they should be, but because of the cycling, get little cooling particularly when it's above 110. Is this a blockage, or is there a valve in the passenger compartment not working properly?
I got one recomendation to add freon, bought a charge kit with a single gauge but the temp (too hot to touch and low pressure so cold as to condense, and to hold on to) of the lines indicates (to my unknowledgable mind) that I probably have an adequate charge.
The mechanics I called said they would have to remove all the R134 and add leak detector, and new freon/oil after fixing, and estimated at $150 if just a hose leak. More if a seal. I'd rather not put this much $ into it.

If it still looks like low chage I'll add some, but had trouble finding low pressure input. High pressure input is quite apparent. Do I add to the HP line with the AC off instead of the LP line with it running?

 

Seems just to be low, can't hurt really to recharge first before $$$ add up. You'll probably read on here in this section about people with similar problems, me alot, ended up to be typical low refrigerant.

 

Add to the LOW Pressure port while running.
Its low, about 1 can.

 

Guess I'll have to find that LP port, but it sure isn't obvious.

 

low pressure port is located by the fire wall, it's on what looks like a silver canister, i just added 1 can to mine at the begining of summer, with the high milage i used a synthetic r134, it cycles due to low freon pressure,(pressure safety switch)

'97 f150 155,000 mls