Car surges when a/c is on

[pwilliams]

Does anyone know what would cause my car to surge while holding a steady speed? It only does this with the a/c on. (00 GT 5spd)

 

[Kilgore Trout]

Low freon.

 

[00GTpony]

same prob in my 00 gt

 

[Az Pete]

My '00 GT Vert did it bad and the A/C was real low. Now that it is filled properly, it only surges once in a while when idling.

 

[the98stang]

Check the cycling switch. It is located on the passenger side firewall. It's a black cylinder lookin' thing. Short the switch by connecting both prongs inside the switch with a paper clip. Turn on the AC for a few seconds, and see if the idle stops jumping. DO NOT run the AC longer than a minute like this, or you can screw it all up. If the idle levels out, you need to replace the AC cycling switch.

 

[pwilliams]

A/C blows cold like the system has just been charged. Could it be a plug or coil pack?

 

[Kilgore Trout]

It is either low freon or cycling switch like we already said. Check both.

 

[rron91]

I have a 2000 gt that does the same thing. The A/C is charged and it only does it in gear. The A/C does not cycle on/off only the engine surging, I think the A/C is putting a load on the engine and pulling the idle low enough for the computer to think it is going to stall and it pushes it back up. I havent figured out how yet.

 

[the98stang]

A/C blows cold like the system has just been charged. Could it be a plug or coil pack?

Did you even read what I said?

 

[steve_stang2003]

Check the cycling switch. It is located on the passenger side firewall. It's a black cylinder lookin' thing. Short the switch by connecting both prongs inside the switch with a paper clip. Turn on the AC for a few seconds, and see if the idle stops jumping. DO NOT run the AC longer than a minute like this, or you can screw it all up. If the idle levels out, you need to replace the AC cycling switch.

+1
Or the freon could be low.
That switch senses low pressure and will cutoff the A/C when the pressure goes low either normally, so the compressor doesn't frost up, or abnormally if the freon level is low.

 

[the98stang]

He said it blows cold like it normally does...I'd bet both my legs it's the cycle switch...

 

[cjb7804]

Mine was doing the same thing. I replaced my cycling switch today and seems to have fixed my problem. Give it a try. Part only runs about $10.