Truck = 97 f150 4.6 auto.
Ac clutch is not coming on I have not checked the low or high side switches yet. With my gauges on what should my static pressure be that is with engine off both gauges hooked up they should both be the same correct? My static pressure is 93psi both sides. Outside temp is 92f When I start the engine AC on max temp, temp dial all the way to cold, fan on high. My question is even if the freon is low should the clutch short cycle until I add freon or will the clutch stay off until I add some freon? . My pressure chart says at 92f my low side should be 108psi with engine on ac on. Does this chart reading look correct?
Thanks in advance
Airborne
Bragg forever

 

The cycling switch should engage at anything over 42-45 psi. Expected static pressure can be looked up on a PT chart for R134a and should both be the same on an equalized system.

Go over to the HVAC sub-forum and read the FAQs. Some good information there to get you started.

 

Thanks SHO I will check out the sub-forums. I'm going out now to check clutch fuse under dash position 5 15a. Owners manual does not show a relay for clutch I thought that a little odd. Must be a low current draw.

 

No, it's actually a couple of amps. The switches were "high-current" versions.

Go back and re-read your original thread about this from a month ago.

 

Thanks again SHO
I just got out of the hospital ( colon cancer) and last month is a blur damn drugs they are damn if you do or damn if you don't. But this truck gives me something else to think about. So once again I double checked the fuse it is good next step is to jump out high side sw. it is easy to get to then low side damn engineers. I can not get under the truck now to power up the clutch so stay tuned.
Thanks alot
Airborne
BRAGG for ever

 

I would simply jump the low switch and see if the compressor cuts on. The high switch is normally closed and pops open around 450psi.

 

You can fine tune your cycling pressure switch using the screw under the connector
That is also what you do to get a non working one to play in some instances
Yours is just low on freon and the contacts are staying open due to the lack of freon?
Added that bit about the screw just to get you all thinking
We / I would never replace the cycling switch without playing with the screw in an attempt to verify that it was the culprit
Of course, you have a gauge set on the vehicle and you have 80 to 90 lbs on both sides to start with

 

Well that is nice to know on the low side sw. Is there a easy way to get to it with all that crap above it? I did not look real close will that whole wiring box unbolt from the firewall? Or am I not looking close enough? I would like to meet the person who designed that frigen layout

 

Airborne, sorry to hear of the health issues... I have a '97 F-150 (382K), 4.6V8 since new... love her... so this link was the issue I had with my A/C and Manic and others held my hand thru it all and we came out perfectly.
https://www.ford-trucks.com/forums/1...n-nothing.html
I get not being able to 'crawl around' as much these days... me too ... hang tough (I bought a new Motorcraft Compressor, was the original, is wonderful now) AND I bought and will always use a 'freon sniffer' NOT the 'U/V' light tool. Good luck!!!!

 

Good man buying a new Motorcraft one Roamingdoc
Airborn, replace your clutch cycling pressure switch (cheap and easy) (it lets out one little puff of freon as you unscrew it, and will not leak any freon out)
Good luck with your health, take the nasty drugs and stay on top of the pain

 

Do you have power at the CLUTCH ?? Your switches might be OK and your clutch air gap is too large ?