how is everyone?

I have a little problem, so when the AC is turned on and while driving slowly or waiting in traffic it repeatedly shuts down and turns back on blowing normal temperature air (same as outside), in addition a hiss from the vents can be heard every time that happens. However, when driving at higher speed, it functions normally, blowing cold air.

I recently had a problem with the radiator fan controller module failing, and the AC doing the same thing. So I though it may be to prevent the car from overheating due to the fan not turning on. The module has been replaced not too long ago, and the fan now turns on, however the AC is still malfunctioning.

Does anyone have an idea why this is? Does it just need refrigerant, or is it more serious? Thank you in advance.

  • Welcome to Motor Vehicle Maintenance & Repair! Commented Jan 24, 2020 at 13:48

1 Answer 1


To me it seems as though it might be low on refrigerant. Probably not hugely low, but low nonetheless. I'd take it to an A/C repair shop and get it tested. I bet you'll find it needs to be topped off. You could possibly DIY this, however, if you get it wrong you can end up blowing out seals from putting too much refrigerant in it (it also depends on what type of refrigerant is needed for your system ... if R12 or R1234yf you're pretty much outta luck ... only R134a would be available to you at a reasonable cost as a consumer).

The bigger question here is why is it low in the first place? There may be a leak in the system. While more expensive, you may want to have the whole system checked for leaks.

  • Or the condenser fans are not working.
    – Moab
    Commented Jan 24, 2020 at 19:52
  • Yup, looks like the fan was connected with inversed polarity, blowing the wrong way.
    – Sunny_Z
    Commented Jan 26, 2020 at 7:15

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