Intermittent a/c on "05 Ranger

[6herald6]

My a/c blows cold air once the compressor clutch engages. Sometimes it takes a half hour before it engages, most times it doesn't engage at all. The connector at the compressor looks good. Could it be a bad a/c relay? Thanks for your help.

Fred

 

[RonD]

AC is a little more complicated in 2005 model

The engine computer(PCM) is involved.

AC systems have 2 pressure switches, a Cycle switch(low pressure), and a High pressure switch.
On older systems these passed the 12volt power to the Compressor, if 1 was "Open" then no compressor.

On your system these are the Ground for the Compressor Relay, but it passes thru the PCM.
So PCM has control of AC relay.
PCM also looks at engine temperature, if it is high it won't start or will cut off AC
If you have a 4 cyl engine then there is also a Head Temperature sensor that needs to be cool or no AC.

I guess the first thing to check is the compressor voltage with AC on, remove the connector put a volt meter on both wires, start engine and turn on AC.
If you see 12volts steady on the compressor wires then the problem is the compressors Field Coil/Clutch it is not working like it should, these can be "shimmed".
Google: Ford AC compressor air gap

If no 12volts then problem will be elsewhere.

Next test would be to test the 2 pressure switches, you need an OHM Meter.
Remove the connector on the switch and put ohm meter probes on both terminals, you should see 0 OHMs, switch is closed which is what it needs to be.
If one is open then could be you are low on refrigerant or have a block in the system.

Next would be to make sure there are no Codes, no CEL(check engine light), if a temp sensor is going out then NO AC.

You can replace AC relay, it is just a standard car relay, in engine fuse box, but that would be a long shot, they don't fail very often.

 

[Squatcho]

Older thread I know, but I'd be interested to know if you ever resolved this issue.

My truck is a 2004 2.3, and while the AC works, it often takes five minutes after a cold start for it the compressor to engage and begin working. After that it works fine until the next cold start.