I've had Firestone look at my truck twice in the last week. Last week they vacuumed and recharged the system with new freon and dye. Today they checked and said there no leaks that they can see. The air coming from the vents is barely cool, and the compressor isn't staying on more than 3-5 seconds. According to Firestone the system is charged properly and should be working. Anyone have some advice?
Odd that Firestone didn't see this cycling?
Which is not normal with AC on
As said by Kaylynn the AC Clutch may need to be re-shimed
AC clutch works by making the "coil" behind it into an electro-magnet, this pulls in the metal clutch plate engaging the compressor
If the metal plate is too far away then magnetic field can't pull it in or can't hold it in, engaged
Easy test for this is to use a volt meter or 12v test light on the 12v wire at the compressor, the not black wire, lol
With engine running, and AC on, test the wire, while its still connected
If you see 12v and compressor cycles OFF then re-shimming may work
If the 12v goes OFF when compressor goes off then the system is shutting off the compressor, not a shim issue
There is an AC clutch relay in the engine fuse box
In 2001 the computer controls this relay
You can put your finger on this relay and if you feel it "clicking" when compressor cycles on and off then could be relay is "weak" or computer is cycling on and off the compressor for a reason
There are two pressure switches, high and low
These can wear out
High pressure switch prevents hoses from "blowing off" if pressure gets too high
Low pressure switch prevents compressor from burning out if fluid runs low, the fluid lubricates the compressor
Either switch is "hot swapable", meaning the switch can be removed and replacement installed without draining the system
Computer would shut off compressor if either switch "opens", then re-start compressor when it "closes" again
Heater
Heater is way more powerful than AC
It has 190degF coolant
AC has 40degF "coolant"
If you want cab temp to be 70degF heater has to be off, lol
The TEMP knob, on 1995 and up Rangers, controls an electric Blend Door
Blend Door directs air from the fan thru the heater core(HOT) or around the heater core(COLD) and anywhere in between hot and cold
This has no connection to AC Compressor cycling on and off, just an FYI
With AC OFF, if you can control TEMP by turning knob and air gets warmer and cooler then Blend door is working
AC has on ON or OFF, there is no temp control other than the Blend Door
MAX AC just closes the Fresh air vent, so fan pulls in air from the cab to re-cool it, versus hotter outside air
It also activates the Heater Bypass Valve in engine bay, has a grey vacuum line, shuts off coolant flow thru heater core in the cab