Air Conditioning problem "HELP"

cudaz101 · #1 (**permalink**) 07-07-2007, 12:59 AM

So the problem is: AC on blows hot air | AC Clutch not engauging | High & Low Pressure is GOOD...

I am thinking it is one of the sensors. Not sure of the terminology for them but the one located on the Highside (Front) & Lowside (Firewall) mounted on top of the dryer can?? Or could it be the Clutch Armature??

Any input or Diagrams would be greatly appreciated.

Cheers,

Brad

projectSHO89 · #2 (**permalink**) 07-07-2007, 07:57 PM

How can you possibly know the the low and high side pressures are GOOD when the compressor won't engage.......

Start by identifying your vehicle FULLY.

cudaz101 · #3 (**permalink**) 07-07-2007, 09:04 PM

Quote:

Originally Posted by projectSHO89

How can you possibly know the the low and high side pressures are GOOD when the compressor won't engage.......

Start by identifying your vehicle FULLY.

99 5.4 expedition "Thought is was in my sig. but I guess its not"...heh

The pressures look good in that the high side is @ 130 & the low side is @ 115 with no pump activity. W/Pump activity I am pretty sure it would be in the correct range. The system worked flawlessly and all of the sudden the clutch does not engauge.

I know its not rocket science here and it should be easy to narrow down. I just thought someone else may have exp'd the same scenario and give me a bit of a lead. I don't like taking my chit to the shop & its definatley not my first rodeo.

After tinkering with it today I come to the same conclusions. High or lowside sensors or the clutch coil.

Thanks,

Brad

projectSHO89 · #4 (**permalink**) 07-08-2007, 06:53 AM

If the compressor is not operating, the pressures HAVE TO BE THE SAME on both sides. They cannot be different. I suspect your guages might just be reading a bit off compared to each other.

See the other thread I posted in last evening. If gives good starter info.

Steve

projectSHO89 · #5 (**permalink**) 07-08-2007, 09:03 AM

Here's the electrical schematics:

1999 Expedition HVAC Schematic.pdf

Steve

lsrx101 · #6 (**permalink**) 07-08-2007, 10:02 AM

Here's 2 quick checks to make that take no tools and about 5 minutes:

-Bump the compressor clutch with a broom stick or other siutable device. If it kicks in, the gap is too wide. If not:
- Locate the Low Side Cycling Switch on the accumulator. Jumper across the connector and see if the clutch engages. If so, the switch has failed. (The pressures you gave may not indicate a proper charge, but they are high enough to close the switch).

If both of these tests fail, check for B+ and Ground at the compressor connector. If none, work your way back through the system to see where you lose voltage..