I don't know what is wrong, but when I turn on my A/C, everything is fine, but when i shift into reverse and have my foot on the brake, the car begins to shake violently...took it to a mechanic, but he said everything was fine...any suggestions??? Thanks.

 

Your symptom is usually caused by too low idle speed under load. When idle speed drops low the 4-cylinder engine vibration increases dramatically. It helps to say what engine/year Accord you have.

The engine controller should be able to maintain engine idle speed under load by increasing air flow through the Electronic Air Control Valve (EACV). However, the EACV can become clogged w/ oil/dirt crud from the PCV air entering the inlet.

Fix is to disconnect the EACV from the throttle body w/ coolant hoses remaining intact and cleaning EACV in place w/ throttle body cleaner. Avoid wetting the EACV solenoid since the cleaner can damage the coil winding of the solenoid.

Also clean the throttle body opening and around the throttle plate w/ throttle body cleaner and an old toothbrush, not a wire brush. Wipe down w/ clean paper towel after drying.

good luck

 

Its a 1991 Accord EX...non-vtec.
Thanks alot, i'll try that. =]