My A/C turns off and on at seemingly random times. When it is on it's cold. According to my mechanic, my car has been very well maintained and the engine is in great shape, but they mentioned the following possible issues with the A/C:

  • Failing Schrader valves
  • Low coolant

I'm not sure what the actual problem is, though, and I'm wondering how to start troubleshooting.

(Unrelated: The mechanic also said the motor mounts may need to be replaced but I'm not sure what to do about that.)

  • I'm voting to close this question as off-topic because you're asking us to interpret the motive of another human being. There is no way that we could divine their intent, even if we knew this individual. – DucatiKiller Aug 17 '16 at 5:43
  • 1
    Take it to a second mechanic, if he mentions the same repairs you know it's legit, Also read the following question or google 'symptoms of bad motor mount' to see if you're experiencing any of these problems. mechanics.stackexchange.com/questions/15170/… – MooseLucifer Aug 17 '16 at 12:40
  • Welcome to the site - in general, we tend to shy away from price-only questions on the site. The situation is so specific to an individual situation that it becomes out of date or irrelevant too fast. That said, please come by the chat any time. Our discussion there is much more free form (and we are very sympathetic to the "pink tax" problem). chat.stackexchange.com/rooms/340/the-pitstop – Bob Cross Aug 17 '16 at 13:32
  • For those commenting, this question could be improved by underlining the mechanical questions a bit more. E.g., "Is it reasonable that a Schrader valve could be failing on a 1995 vehicle?" "Should I really expect to see failing motor mounts on a 21 year old car?" – Bob Cross Aug 17 '16 at 13:33

While I cannot speak for the intent of the mechanic, or the costs incurred (every vehicle is different) I can answer some points in your questions.

Schrader Valves:

Replacing the schrader valves will require a system vacuum and recharge as if the schrader valves leak, the freon has escaped and has likely normalized with atmospheric air. This means that the system has become contaminated and will need to be flushed, vacuum drawn, and refilled. It is a very time consuming process, especially if other leaks are present, which can be found once a vacuum is drawn on the system.

Motor Mounts:

As for the motor mounts, It depends on the mileage of your vehicle. Some vehicles are prone to premature motor mount failure. If your vehicle leaks, or has not been maintained regularly, this can also contribute to mount failure. Replacing all of the motor mounts should not normally be necessary, however I've run into cases where literally every motor mount had to be replaced, and that in itself is not an easy feat. The motor must be supported, and some mounts may be in difficult portions of the engine bay and may not be easy to get to.

Bottom line:

You should always go get a second opinion. Do not take one mechanic's word for it, especially if you feel or suspect he's giving you a run for your money.


Repairing almost anything on an AC system requires the system to be refilled with coolant, and the procedure costs about $140 for most vehicles (this is completely different from topping up a system that is still sealed). This needs to be added to whatever the actual repair cost is.

As for your motor mounts, they do tend to go bad with time and mileage. Is there any chance you can pop the hood and take pictures for us? Motor mounts and big honking things attached to your engine and the car. There's usually 4 of them, look in front, behind, left and right. Replacing these can be fairly substancial.

Here's an example of one


More than likely you have leaking o-rings on the AC springlock connectors.

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Discharge system, Replace all o-rings on all spring lock AC connections, be sure to Not score the soft aluminum when removing old o-rings. Lincoln specified thicker o-rings under a TSB (Technical Service Bulletin), so get the improved o-rings from Ford. Clean spring lock coupling connectors and o-ring grooves with maroon colored 3M Scotch Brite (cut in strips) before installing new o-rings. Re-charge system.

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