Ford Ranger AC issue

[Kyzrsoze]

The AC on my 2004 has an odd issue that I haven't seen before. After a cold start, it takes up to 5 minutes for the compressor to engage. Once running the air blows cold and works fine until the next cold start. I've checked the coolant level and its fine. I installed a new low pressure switch, mainly because it was cheap part. I checked resistance on the high pressure switch and it reads 0.

 

[avmtdan]

Check voltage at the compressor. My mom's mustang did something similar due to the relay going bad. If you aren't getting battery voltage at the connector with the truck running and ac on, look for the multifunction box to be the culprit.


If it is theasy multifunction box an expensive box with a $3 relay in it. Easy soldering fix if your capable, otherwise around d a $200 part.

 

[avmtdan]

Make that if you are getting less than battery voltage, but more than zero volts. Hers was around 8v cold, as the relay box got warmed up the relay would eventually put out just barely enough to engage the clutch.

 

[Kyzrsoze]

Make that if you are getting less than battery voltage, but more than zero volts. Hers was around 8v cold, as the relay box got warmed up the relay would eventually put out just barely enough to engage the clutch.

Good info, thanks. Is there another relay in the truck that can be swapped in place for testing?

 

[Bucket99]

Check for excessive resistance in the clutch coil

 

[Kyzrsoze]

Decided to swap the in wiper relay and promptly dropped it into the abyss of the engine bay. At the store buying two relays now.

 

[rOmiLaYu]

Decided to swap the wiper relay and promptly dropped it into the abyss of the engine bay. At the store buying two relays now.

 

[Kyzrsoze]

My expectation was that a relay would fail more like a fuse. I've got a new relay installed and I'll need to try it on a cold start in the morning.

 

[avmtdan]

Relays do dumb things. Seemsmost intermittent issues i have dealt with points to relays. You can also jumper the relay socket to force the clutch to work, but this negates the safeties. If a relay is falling sometimes the bumps from driving free them up, that or the heat eventually allows it to function.

Looks like the 04 ranger doesn't use a big relay box, so cheap way to troubleshoot and fix if it's that. Earlier Mustangs used a big relay box that had 3 relays internal soldered to a board.

 

[Kyzrsoze]

Check for excessive resistance in the clutch coil

Good call. If I still have a problem on cold start tomorrow, that might be my next move.