A/C Nightmares
Thread Starter
Junior Member
Joined: Mar 2021
Posts: 22
Likes: 0
From: OH
I was also thinking about that low-pressure switch too, but I don't know enough about these newer trucks to suggest the bypass trick you're talking about. I did this trick on my old 94 Ranger when it was having trouble. It sat for years and I guess that switch froze up. Installed a new one and it was good to go.
If these switches are bad - your clutch is going NOWHERE ! Be careful though: I read that you do NOT want to fill your system with that switch bypassed. It can get you into some serious trouble (apparently some people try and fill them this way).
If these switches are bad - your clutch is going NOWHERE ! Be careful though: I read that you do NOT want to fill your system with that switch bypassed. It can get you into some serious trouble (apparently some people try and fill them this way).
Senior Member
Joined: Sep 2020
Posts: 106
Likes: 32
low pressure switch
Low pressure switch located on the drier / accumulator, Auto Zone shows to be in stock Santech A/C Switch MT0887 (low pressure) and MT0611 (high pressure).
And poking around Rock Auto, you will find them here
FORD > 2004 > F-150 > 4.6L V8 > Electrical-Switch & Relay > A/C Clutch Switch
Goodluck!
And poking around Rock Auto, you will find them here
FORD > 2004 > F-150 > 4.6L V8 > Electrical-Switch & Relay > A/C Clutch Switch
Goodluck!
Last edited by Ron R; Jun 25, 2021 at 11:49 AM.
05 5.4l 3v s.crew lariat
Joined: Oct 2009
Posts: 3,505
Likes: 672
From: fl
Well I don't know for sure but it seems to me that if you can hold full vac you can fill system with liquid -can up side down to the measured amount rated on your nameplate. That vac will pull that liquid right in there very slowly if I were you . .
I charge mini splits this way its very accurate. Let the system equalize before you run it . I have a digital weight system and I run vac to below 500 microns for 10 minutes with pump off . You probably can use two 1 pound cans to get close but not with ac running . Leave it quite awhile to let gases equalize in system
But you should be able to trouble shoot your clutch signal with a test light , you can even cut the top off your old relay and push it in to bring clutch on .
Do you know for sure that ground on ac clutch is good ? Use your test light connected to positive 12vdc .
The pcm is not going to pu clutch relay with either high pressure or low pressure.
Some on here may have a better method on auto ac .
I charge mini splits this way its very accurate. Let the system equalize before you run it . I have a digital weight system and I run vac to below 500 microns for 10 minutes with pump off . You probably can use two 1 pound cans to get close but not with ac running . Leave it quite awhile to let gases equalize in system
But you should be able to trouble shoot your clutch signal with a test light , you can even cut the top off your old relay and push it in to bring clutch on .
Do you know for sure that ground on ac clutch is good ? Use your test light connected to positive 12vdc .
The pcm is not going to pu clutch relay with either high pressure or low pressure.
Some on here may have a better method on auto ac .