A/C, fan clutch? my numbers are.....
07 Expedition w/aux rear air, 172,000 mi, well maintained.
92 deg days in south Florida I'm noticing A/C feels warm at idle but not bad under speed so I took some readings: Engine off: 90 psi low & high, Amb 84 deg (Gauge Manifold is Mastercool brass) doors open, a/c on max cool, fan high: Speed 1500 rpm Amb. 84F Low 20psi High 212psi Vent Temp 58F So I added 134a until I got the following: Speed 1700 rpm Amb 84F Low 30 psi High 275 psi Vent temp 55F @idle: Low 40 psi High 250 psi Vent temp 59F While @ idle or slightly higher I heard the fan clutch kick in (and wind noise), immediately the head pressure dropped to about 190-200psi, low dropped to 30 psi, and vent temp started dropping to 50F and below (48F) but didnt stay more than a few minutes. Engine off, new high/low pressure is 96F w/ amb of 83F. At ilde it almost looks slightly over charged. Shouldnt the fan clutch remain on at idle? How can I check or is it better to just replace? Not sure what cycles it, engine coolant temp? refrigerant head pressure? is there a way to test? IT was spinning the whole time while taking readings but there was a noticable change when it kicked in. Thanks for any thoughts. |
Controlled by a thermostat built into the clutch. What engine?
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'07 Expeditions are all 5.4 V8.
-- Chuck |
Engine is 5.4L all stock, all original except for one new plug coil, idler pulley, minor misc. A/C control panel was replaced under warranty at 35,000 mi.
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Try using a fan to push air accross the condenser to check the pressures. I think the new models use electonically controled fans. My 08 F150 had a pair of wires going to the fan drive. The clutch fan may be doing what it is designed to do.
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