Car surges when a/c is on

P

pwilliams

New Member

Aug 26, 2006

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GA

May 29, 2007

#1

• May 29, 2007

• #1

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)

 

K

Kilgore Trout

Fried or Broiled ?

10 Year Member

Mar 30, 2005

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May 29, 2007

#2

• May 29, 2007

• #2

Low freon.

 

00GTpony

Member

Mar 10, 2007

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16

May 29, 2007

#3

• May 29, 2007

• #3

same prob in my 00 gt

 

Az Pete

10 Year Member

Mar 30, 2005

711

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49

Panama City, Fl.

May 30, 2007

#4

• May 30, 2007

• #4

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

Active Member

Aug 12, 2005

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Clovis, CA

May 30, 2007

#5

• May 30, 2007

• #5

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.

 

P

pwilliams

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Aug 26, 2006

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May 30, 2007

#6

• May 30, 2007

• #6

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

 

K

Kilgore Trout

Fried or Broiled ?

10 Year Member

Mar 30, 2005

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May 30, 2007

#7

• May 30, 2007

• #7

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

 

R

rron91

New Member

Oct 1, 2007

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Oct 3, 2007

#8

• Oct 3, 2007

• #8

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

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Aug 12, 2005

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Clovis, CA

Oct 3, 2007

#9

• Oct 3, 2007

• #9

pwilliams said:

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

Click to expand...

Did you even read what I said?

 

S

steve_stang2003

New Member

Apr 18, 2007

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Oct 3, 2007

#10

• Oct 3, 2007

• #10

the98stang said:

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.

Click to expand...

+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

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Aug 12, 2005

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Clovis, CA

Oct 4, 2007

#11

• Oct 4, 2007

• #11

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

 

C

cjb7804

New Member

Oct 5, 2007

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Rapid City, SD

Oct 5, 2007

#12

• Oct 5, 2007

• #12

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.