Recently my air condition started giving cold air off and on and it really wasn;t that cold. I got a can of Sub Zero and it only took a small amount to bring it up to the OK range. The compressor kicks on ,there is no noise and it sems as though it does better at certain rpm's. Should I get a recovery tank and bleed off what is in there and refill with new ? BTW the serpentine belt does not appear to be slipping. The truck has 296,000 and this is the first problem I have had with the air. In fact I have never had a problem on any vehicle with air conditioning. Any advice?

 

Is the compressor Clutch cutting in and out

https://www.ford-trucks.com/forums/5...-problems.html

 

Does your ac only act up when sitting still or while driving? If when sitting still it acts up, I would check the fan clutch for enguagement. If there is no air flow over the condensor, too much pressure builds and the pressure sensors kick out the ac compressor.

 

Ac clutch is working. Fan clutch was never checked. Will check it tomorrow.

 

Mine did the same thing last summer. It turned out to be a short in the plug of the harness that plugs in to the AC compressor (on top of it). Got a new one form the stealership and it took care of the problem. You can get just the plug with wires to slice, in other words you don't have to buy the whole wiring harness. Hope this helps.

 

My A/C was doing the same thing while I was pulling my trailer. If I stopped it started to blow hot as ever, and then when I would start to drive it would blow cold again. Sounds like I need a fan clutch, how do I check it to make sure thats is the problem? When I opened the hood with it running and the A/C on the clutch was not engauged. Fan was turning.

 

Fan Clutch Test

Spin the fan blade (8600) by hand. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:
Fan Clutch Test—Minimum Speed Requirement

Use a suitable marker to mark the water pump pulley (8509), one of the fan blade retaining bolts and the crankshaft pulley (6312).
Connect a tachometer to the engine.
Install a throttle adjusting tool.
Connect the Digital Photoelectric Tachometer.
WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation.

Start the engine and run it at approximately 1,500 rpm until the normal operating temperature has been achieved.
Operate the strobe light at 4,320 rpm for 5.4L and 6.8L engines and 3600 rpm for 7.3L diesel engines, and aim it at the water pump pulley. Adjust the engine speed until the light flash and the water pump pulley mark are synchronized.
Aim the strobe light at the fan blade bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade bolt (the fan blade appears to stand still).
The fan blade speed must not be greater than 1,900 rpm on 5.4L engines and 2,000 rpm on 6.8L and 7.3L engines.
Turn the engine off.
If the fan blade speed was greater than 1,900 rpm (on 5.4L) (on diesel engines and 6.8L, 2,000 rpm), install a new fan clutch (8A616).
Fan Clutch Test—Maximum Speed Requirement

Perform Steps 1 through 5 of the Fan Clutch Test—Minimum Speed Requirement.
NOTE: The temperature of the air hitting the fan clutch should be above 96°C (205°F) for maximum fan speed.

Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille (8200). This will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.
Place the climate control function selector switch in the MAX A/C position and the blower motor switch in the HI position.
Adjust the strobe to 4,320 rpm for 5.4L and 6.8L engines and 3,600 rpm for 7.3L diesel engines.
WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation.

Start the engine and adjust the engine speed until the strobe light flash and the water pump pulley mark are synchronized.
Aim the strobe light at the fan blade retaining bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade bolt (the fan blade appears to stand still).
If the fan blade speed is less than 3,600 rpm on 5.4L engines and 3,500 rpm on 6.8L engines, 2,850 rpm on 7.3L engines, install a new fan clutch.

 

Once again your knowledge of our trucks amazes me. I guess I will be going out and buying a timing light for a diesel. lol. I guess I hook it up with the tach wire that I find, correct. And where would I find to connect the tach to.