trashxtrash

Hello ya'll this is my second stang. I'm new to mustangs; I bought an 03 GT and fell in love but sadly it was totalled a month later after a lady ran a red light,

found an 00 vert and haggled down for 3k at 14X,XXX miles

everything works
EXCEPT
THE A/C

When i turn the a/c on, max a/c or a/c
or actually any of the air controls

the idle goes up and down.

I figured it was a low charge so i hooked on a pressure gauge and read 65psi with the engine turned on, 100 psi static with the engine off.

The clutch wasn't engaging and there was no cold air and the idle would go up and down 500 rpms as if it had a vacuum leak.

I haven't worked with HVAC for a while so i was like okay,
maybe it's overcharged?

SO... someone who isn't me was pressing the low side port with a pen to release some freon
they felt normal compressed air coming out (one time it was hot), and then sometimes cold freeon/ pag oil would shoot out, and eventually just freeon and oil came out.


Released all the pressure (wish i had a vacuum pump to pull vacuum but someone stole that out of my storage unit)

and jumped the low side pressure port
and voila
the clutch turned on
and i was able to charge up to 40psi
and cold air was spewing out of the cabin with max ac on


i thought my woes were solved
however once i reconnected the low side pressure port to the drier/receiver

i would get the idle up and down
and no cold air would come out
and the clutch would not engage.



What is causing the clutch not to engage at this point?

I was thinking about getting a new low side pressure sensor and seeing if that solved the issure

or somehow creating a jumper/ switch on off button for the low pressure switch

could there be air in the system and the amount of freeon is incorrect causing the compressor not to kick in?

I'm at a loss here as i'm not well rounded in HVAC

your thoughts and tips are appreciated before i start buying parts (initially thought the compressor was seized so i was ready to get one off of craigslist then read up on jumping the low pressure sensor)

Also i've done some reading around and heard about a sensor that controls the cooling fans and fuel pump hidden in the passenger well but i'm not sure if thats' the case?

please help before i burn in this california heat thank you all!

tadpole1969

get the low side pressure sensor, i had one do this to me and had the same thing going on, high to low idle back and fourth while ac is on

jwog666

so let me get this straight, you or someone else let all the refrigerant out of the system? you may have just had a low side switch problem, but now you need an evac and recharge. if i were u i would take it to a shop with the right equip next time instead of violating several state and federal laws regarding the release of refrigerant into the atmosphere. (face palm)

Soldier GT

Congrats on the stang. Mannnnn why not have a professional look at it. Spend the 80 or,so bucks and stop sweating!

trashxtrash

THANK YOU ALL FOR YOUR HELP

was indeed just the low pressure switch.

Replaced, a/c clutch kicks on ice cold air
and no more loopy idle

Try this before recharging/ evacuating

especially if you already have a healthy charge in your system
and the clutch isn't engaging

THANK YOU ALL!

tadpole1969

your very welcome! glad to see your ac is back up and going