Sticky throttle cable only when using A/C

[98civex]

98 civic ex, I've noticed in the hotter summer days when I use my a/c when my foot is off the gas pedal the idle is high unless I gently tap the pedal or pull up on it from underneath then idle drops to where it should be.

This never ever happens if I'm not using the a/c. How does that make sense?

Also, is it normal for the a/c to blow cold air on really hot days after about 20 min of driving? It's never instant like most other cars.

 

[CO671]

A/C Compressor puts some load on the engine. Check the tension of your belt and make sure its in spec. When climbing hills, you'll notice a difference with the a/c on and a/c off.
Once it starts blowing cold, park, pop the hood and make sure the condenser fan is spinning.

 

[98civex]

So if the belt was out of spec it'd cause the throttle cable to stick?

 

[RonJ]

Sticking --> Clean the throttle body and adjust the throttle cable to have as much as 1/2" of slack. Then go from there.

You can performance test your A/C system using a manifold gauge set and a thermometer:

 

[98civex]

Sticking --> Clean the throttle body and adjust the throttle cable to have as much as 1/2" of slack. Then go from there.

You can performance test your A/C system using a manifold gauge set and a thermometer:

I've cleaned and adjusted the cable. Just odd that this happens only with ac system engaged.

 

[RonJ]

I've cleaned and adjusted the cable.

Sooooo...moving right along...did you clean the throttle body?

Just odd that this happens only with ac system engaged.

Cars throw odd problems at you regularly. The bottom line is that your problem is a near perfect fit for having a dirty throttle body or a misadjusted or bad throttle cable. Start by cleaning the TB thoroughly. The plate is probably just sticking.

 

[98civex]

Yes I've cleaned that too and the idle control valve.

I guess what I'm trying to understand is why when ac is engaged the throttle sticks otherwise its fine?

 

[RonJ]

I guess what I'm trying to understand is why when ac is engaged the throttle sticks otherwise its fine?

The A/C controls the idle speed via the ECU and IACV, not the throttle cable or throttle plate.

The bottom line is that your problem is a near perfect fit for having a dirty throttle body or a misadjusted or bad throttle cable. Start by cleaning the TB thoroughly. The plate is probably just sticking.

Detail how you adjusted the throttle cable and cleaned the TB.

Clean the TB again and/or readjust/replace the throttle cable.

 

[98civex]

I backed off the throttle cable lock nut and loosened the cable to where the gas pedal felt like there was a good 1/2 to 3/4" of play before throttle body started to react.

I removed the intake duct to throttle body, sprayed throttle body cleaner, used a toothbrush to loosen the carbon buildup and wiped clean with a rag. Same with idle valve.

 

[98civex]

The A/C controls the idle speed via the ECU and IACV, not the throttle cable or throttle plate.

Yes I understand but why then only when a/c on would the throttle body or the cable be possibly sticking and not when a/c isn't used?

Also, I noticed this only is an issue when the outside temperatures are really hot. Not sure if that helps diagnose anything.

 

[RonJ]

Yes I understand but why then only when a/c on would the throttle body or the cable be possibly sticking and not when a/c isn't used?

Also, I noticed this only is an issue when the outside temperatures are really hot. Not sure if that helps diagnose anything.

Assuming that the information you supplied is accurate, the throttle plate IS sticking open. I've listed the possible causes. Stop obsessing on why the throttle plate sticks open only when the A/C is on or when the weather is hot because this seems to be paralyzing your ability to think clearly and to move forward.