How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • Go back-and-forth until satisfied
    Rate the answer you receive.
Ask sebastian manrique Your Own Question
sebastian manrique
sebastian manrique, Auto Mechanic
Category: Car
Satisfied Customers: 2038
Experience:  Director Ejecutivo at Multiservicios Cruz de las Mercedes
Type Your Car Question Here...
sebastian manrique is online now

Audi A3 1.9tdi 2009 when I turn on a/c on my car engine

Customer Question

Hello Audi A3 1.9tdi 2009 when I turn on a/c on my car engine start jerking new a/c pump and fully regas still engine jerking when it’s on a/c
Submitted: 16 days ago.
Category: Car
Customer: replied 16 days ago.
Any idea why
Expert:  sebastian manrique replied 15 days ago.

Hi, my name is***** your mechanic automotive expert, and I will be happy to assist you today. In some cases, I may need more information to assist better. I apologize for any delay.

I try to be here most weekdays and some weekends. If you respond and I do not respond back right away I will do so as soon as I can.

Dear customer, when this happen do the RPMs go down when the car stars jerking?

Customer: replied 15 days ago.
I press a/c on the car start start jerking when rpms goes down
Expert:  sebastian manrique replied 15 days ago.

Dear customer, I understand your problem but there is a very important characteristic in your query and that is that the engine loses RPMs, there is a very important part of the operation of the minimum/idle, this component is known as the throttle potentiometer, the Minimum valve is the valve in the throttle body and it is in charge of regulating the minimum rpm load at which the engine is located.

For example, the minimum of an average engine is between 700 and 800 rpm, when the compressor is activated, this increases. The load of the engine and the valve of the minimum potentiometer now tends to open the acceleration a little more so that it can compensate this load and continue maintaining the rpm at these values ​​of 700 and 800.

When the potentiometer has problems, when activating the air compressor, the load can cause the motor to decrease the rpm, sometimes it can even turn off, and obviously this causes vibration and noise in the motor due to this load difference.

I recommend you disassemble the throttle body and perform complete maintenance including the potentiometer, there is the possibility that it must be replaced, you will have to verify it before doing it, as well as its connections and wiring.

Expert:  sebastian manrique replied 15 days ago.

Do you understand me, dear customer?

My goal is to give you the best experience possible and that's why i am sorry for my delay! I hope I have earned a 5 star rating. Please remember to rate my service by selecting the 5 stars at the top of the screen before you leave JA today. If you need more assistance, please use the reply box below and let me know. It has been my pleasure to assist you!
Keep safe.
Kind regards, Sebastian.