Forum Discussion

Big_Katuna's avatar
Big_Katuna
Explorer II
Jun 28, 2018

2005 Freightliner CAT C7 AC belt chirp

Belt and tensioner replaced two years ago (pm).

AC refrigerant level checked and topped off last summer.

Left for Ohio for two months today. Noticed that the belt chirped 40-50 seconds when the dash ac first engaged. After that it would chirp a few seconds when the ac would cycle on. Drove four hours without incident.

I’m pretty sure the ac is on the main serpentine belt so a belt failure is a show stopper.

My fear is that the tensioner or compressor is failing.

I’m thinking I should not use the dash ac and run the genset and roof acs.

Thoughts? Suggestions?
Class A
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    Jul 01, 2018
    It’s not a V belt, it’s a flat serpentine.

    It only chirps when the ac kicks on and only once or twice then quits.

    I’m not using the dash ac, but using the genset and roof ac.
  • down_home's avatar
    down_home
    Explorer II
    Jul 01, 2018
    A lot perhaps most V Belts now made in China and may not be same exact oem dimensions and if so will never grip pulleys right and might even have to replace pulleys if it slips too much and polishes away some of the metal f the pulleys.
    I haven't changed our belts but discovered this several years ago in a car I had.
    Wonder if the hardware is avail able for the new serpentine systems on our cars?
    That fan bearing keeps popping up from time to time with failure off the sealed bearing. The fan has no clutch and keeps turning all the time and a heck of a load.
  • aztortuga's avatar
    aztortuga
    Explorer
    Jul 01, 2018
    Had the same chirping noise on my 2005 c_7. It was the fan bearing going bad. Check your fan bearing for looseness or hard turning. Mine was worse when cold. Some of these have been so bad that the fan will seize and may come off of the bearing.
  • donn0128's avatar
    donn0128
    Explorer II
    Jun 28, 2018
    Take a bar of soap and carefully rub the sides of the belt while running. If your noise stops then you have a belt with smooth sides and its simply slipping. New belt will cure the noise.
  • wolfe10's avatar
    wolfe10
    Explorer
    Jun 28, 2018
    Probably worth removing the belt and verifying that all the accessories and tensioner bearings are good.

    Your fan has a sealed bearing-- check that carefully!

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