A/C blows hot then cold


KJRGT

GT Owner
Mark II Lifetime
May 4, 2006
2,840
SoCal
My AC was taking a little longer to get cold so today I gave it a re charge. Even though the pressure was reading fine, it took some refrigerant and immediately the air was much colder.

Might be worth it to give your GT a hit of 134A even if it's performance seems OK. After ten years and 23,500 miles it gave my system nice little jolt.
 
Last edited:

STORMCAT

GT
Mark IV Lifetime
Le Mans 2010 Supporter
May 25, 2006
7,436
Ft. Lauderdale
This is an old post and I haven't read through everything. Had an issue with my compressor cycling on and off and or not engaging at all. Turned out just to be the AC compressor relay located under the front trunk.
 

Sonic blue

GT Owner
Jun 1, 2007
50
British Columbia
going to hook it up on gauges tomorrow, thanx!
 

Silverbullitt

GT Owner
Mar 3, 2006
1,743
Lago Vista, TX
If it is humid make sure the AC is set on recirculate. Drier air in the cabin will be running across the coil and the chance of icing will be reduced. Mine is a little slow to cool after 6 yrs, but will overcome the tx heat after about a minute, temps are usually around 180, mine is an 06 so there is no grillwork obstructing airflow.
 

roketman

GT Owner
Mark IV Lifetime
Oct 24, 2005
6,838
ma.
I too have had similar issues.I realized two fixes.One is to put in recirculate.The other is to move the temp adjustment knob to medium for just a second and than back to full cold.This seems to solve the problem.Also if you are not aware .The AC shuts off under full acceleration ,for max H.P.,than it comes back on.I believe removing the exit screens may help too.I have not had mine in for years.
 

soroush

Ford Gt Owner
Mark II Lifetime
Aug 8, 2007
5,198
I don't know if is the same thing but my 65K mile blue car was suffering from an AC problem for the last two years, I was just too lazy to really look into it I guess, the Ac blew cold every time the car was started in the morning and would work fine until the temps got up to 200 then it would quit blowing cold air. then it wouldn't work for the rest of that day, the next day same thing.

well I got off my lazy butt this sat morning ran a test wire to inside the car to make sure in fact the compressor was still getting power when the ac started acting up and blowing hot air, and found that to be the case. I took the pulley off the compressor and replaced the electromagnet thats under the pulley a 35 dollar part! now it all seems to be working great!! over the years I talked to so many people regarding this issue we even changed all the pressure switches and the dryer and expansion valve and all along was the magnet. any way just thought this might be useful, btw I did everything while the compressor was still on the car, so I didn't even have to take the lines off so no recharging the system, sometimes you get lucky!
 

Cobraguy

GT Owner
Again...thanks to all for the opinions and/or advice....lots to work with now !
 

2112

Blue/white 06'
Mark II Lifetime
That is great! By chance to you have a picture of the Magnet or where it is on the compressor? I assume you had to pull the belt and pulley to get to it?
 

soroush

Ford Gt Owner
Mark II Lifetime
Aug 8, 2007
5,198
That is great! By chance to you have a picture of the Magnet or where it is on the compressor? I assume you had to pull the belt and pulley to get to it?
I didn't take any pics but I had the compressor off of my "garage table" ;) in anticipation of replacing it with the one in the car, I can take some pics of that later and post. but basically there is a 13mm nut in the front of the pulley that needs to be removed then the "flywheel" part of the pulley comes out behind it there is a C clip that has to be removed in order for the actual pulley to come out, it takes some elbow grease to get the pulley off especially with the compressor still on the car and all not having the best access, but after the pulley comes out the electro magnet is behind it or rather the pulley is around the magnet but slides off a bearing, then there is a second C clip that needs to be removed and the electromagnet come off, the magnet comes from ford with all the wiring and plug plus the limiter built in all one unit, I really think I paid no more than 35 bucks but that one a year ago.
 

Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
Reading the FSM, there are many parameters that shut the A/C off. Most are normal (WOT, etc.). One is perhaps environmental. If the compressor housing temperature reaches 247 degrees F, the A/C switches off.

I can make a case in my mind for that. Hot speed run on a hot day, then stuck in traffic with little air moving through the engine area leading to heat soak.

Would the compressor housing reach 247? IDK. But, it is on the bottom, not far from the exhaust, and enclosed by the belly pan.
 

Kayvan

GT Owner
Jul 13, 2006
4,782