AC blows hot at highway speed

[mdelac01]

Hello LS owners,
This is my first post, but I have been reading this forum for a little while to help me fix the famous coil issues. I believe I'm almost done with that; but today I'm posting about my A/C; hope someone can help; and many benefit from this.

<<Here it is;>>
When I start my LS and turn on the A/C everything seems fine. I've left it on for over an hour running in the middle of the hot sun, and the A/C is cold enough as long as I leave it parked or don't go past 40 mph.

But when I start driving and get past 40-50mph the air conditioner blows hot air on all sides (passenger and driver). FYI I live in south Florida, where it is HOT and HUMID!

Reducing the car speed does NOT bring the cold air back. Usually turning the car off, and waiting a few hours...then I can re-use the AC...but can't go any faster than about 40-50mph when the cold air stops again.

The car is LS Sport V8.

<<A little more info: I've noticed that just before the AC will stop working the car starts to sputter, and I get the CEL blinking...which is always some COIL misfire. But as I mentioned I'm fixing that with all the great info from this forum. Can one thing be related to the other?>>

I hope I'm not repeating anyone's question; I tried seraching for it and did not find it...sorry if I did, just ferer me the link if so. Otherwise ANY IDEAS?
Thanks in advance.

 

[oldhead]

If your misfiring bad enough the A/C will not come on.

 

[joegr]

It would help to know if you have a gen I or gen II LS.
Gen I = 2000-2002
Gen II = 2003-2006.
It makes some difference in the symptoms of a failing DCCV.

Does it go to blowing very hot (heated) air, or just warm (not cooled) air?

You really need to fix the coil/misfire issues before trying to run this or any other problem down. When the coils mess up on the LS, they generate lots of electrical noise. This noise can cause other systems, like the climate control, to mess up. Also, as was said, the PCM will lock out the AC compressor when certain faults are detected.

 

[mdelac01]

I missed the year! It is a 2002 LS V8 Sport (Gen 1)
Very interesting to know that the PCM can lock out the compressor on certain faults!

Like I mentioned, I'v been working on my misfire based on all the info from the forum.
-Changed the head cover gasket with Motorcraft redesigned models.
-Replaced all the spark-plugs with new Motorcraft.
-Changed all the COILS with new coils (2 motorcraft and 6 Duralast) don't ask why ;-)
-New Air filter

I finished the job last night. Today I drive the car and I noticed that it drives 10 times better...but still not right. It still stutters at about 40-45, but definitely not as bad as before the coil changes. Also, the CEL light came on again.

TONIGHT I plan to read the codes again, and clean the MAF.
I will post the results.

To answer the question: The air seems to be not cooled (instead of hot from the heater) when the issue happens.

>>>Based on what you posted it seems that yes, my misfires may be causing the A/C to stop cooling. I hope cleaning the MAF sensor helps with the misfires.

Any other suggestions? I like my LS , I really want it to run smooth again...and of course for the AC to work!

 

[mdelac01]

HAPPY ENDING!!!
I'm so happy! After completing all the changes:
-Changed the head cover gasket with Motorcraft redesigned model.
-Replaced all the spark-plugs with new Motorcraft.
-Changed all the COILS with new coils (2 motorcraft and 6 Duralast) don't ask why ;-)
-New Air filter
-Cleaned the MAF

Now my 02 Lincoln LS V8 is back to its old self (No more misfires)
And, to top it all off, the AC issue is fixed. It continues to work even at highway speeds.

So glad, I spent some good quality time washing and putting leather conditioner on the seats!

Thanks to this forum I was able to do this myself. Saved some $$$.

Ok...so the lesson learned is that as oldhead and joegr said when misfiring, the compressor may shut off or not come on at all.

Thanks again.