Another AC problem

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Jun 23, 2013 | 05:50 PM

firemand

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Another AC problem

Hello
2003 F150 5.4 with 100,000 miles
Problem: ac cuts out during normal (not hard) acceleration, now its still doing that but now worse it only blow at a temp of about 70 degrees. yesterday it started to change temp (slightly) but enough to feel during normal highway driving. No changes in fan speed or which vent the air is coming out of. No sound heard from opening or closing air vents. Does it on ac max and normal ac.

Compressor air cap .026
Checked all vacuum lines No leaks (checked under hood and in dash)
AC clutch IS engaging
AC pressure (using and ac manifold gauges)
AC max clutch engaged H 225-205 L 35-32 (gauges vary)
Normal AC clutch engaged H 225-230 L 38 (gauges vary)
AC off clutch no engaged H125-130 L 200ish
Truck off H 125 L 115
I live in Las Vegas so I need the ac
Help before I take it to the Stealership

Thanks for the help

Jun 23, 2013 | 05:58 PM

JWC 3

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From: Tennessee

Have you checked your temp blend door ? The actuator may be bad and not blocking off the heater fully .

Jun 23, 2013 | 06:02 PM

firemand

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Is there a way to check it. when it turn the **** on the dash it defiantly does change the temp

Jun 23, 2013 | 06:09 PM

JWC 3

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From: Tennessee

You can pinch off a heater hose to block flow and see if that helps . If it does you have a blend door issue . Actuator , door , binding or obstruction . I have pulled all sorts of things from heater/ac boxes . A kitchen knife once , explain that one .

Jun 23, 2013 | 08:33 PM

firemand

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With heater hose clamped temp was the same no change in ac.

Jun 23, 2013 | 08:45 PM

JWC 3

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From: Tennessee

Ok , your gauge readings are while sitting . Do you have proper air flow ? ( fan clutch , clean condensor ) Scratch that ... drop your air gap to 14-17 and see how it does .I have had to remove all shims to get some systems to work ( worn out but still can work for a while ) .

Jun 26, 2013 | 01:55 PM

firemand

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More questions.

Is this normal
While sitting at idel with ac max compressor engaged the whole time.

When I increase rpm it cycles on and off about every 4 sec engaged for 4 and un engaged for 4. AC max

Small amount of air flow from bottom vent (the one covered by the black plastic piece and from the small vent on dash by A posts). Same amount od air flow no matter what the fan speed is. AC max and normal ac

Are all my gauge reading within spec? IE do I need to add freon
How can you check for proper operation of the blend door
Could the problem be my low pressure cut off switch (friend told me it may be that)

Again Thanks for the help and input.

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Jun 27, 2013 | 07:30 AM

projectSHO89

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From: St Louis

Quote:

Is this normal
While sitting at idel with ac max compressor engaged the whole time.

Vegas in the summer? You bet it's normal.

Quote:

When I increase rpm it cycles on and off about every 4 sec engaged for 4 and un engaged for 4. AC max

Might be normal, might not. Need corresponding gauge readings. To me, it suggests a slightly low refrigerant charge but without gauge reading, it's only a guess since the high side cutout switch can also cause cycling although I'd expect it to cycle at a much slower rate.

Quote:

Could the problem be my low pressure cut off switch (friend told me it may be that)

Again, gauge readings would be needed to assess the switch's operation. Usually, they should engage around 45 psi ascending and disengage around 22 psi descending.

Your 03, if memory is working, uses a PCM-controlled clutch relay. With a scan tool, you can go in and view the PID to see if the system is requesting compressor operation and the commanded output state of the PCM as far as the clutch is concerned.