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1996 Suburban A Few Problems

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by meenkeene518, Aug 21, 2008.

  1. meenkeene518

    meenkeene518 New Member

    Hello,

    I have a 1996 Suburban with about 195000 miles on it, and i have a few problems. the heater doesnt always blow hot air even when the engine is up to running temp. It seems to cut in and out when it pleases, but when i get to about 2000rpms the heat kicks in and it very hot. i think its a vacuum issue, but im not sure.

    Second i have barn doors in the back and my right side door has no working defroster ( if your facing the back of the truck, the one with the outside door handle) and the other door only defrosts the middle 1/3. i cleaned the contacts on the 5 prong unit and where the connect to the module. any thoughts?

    thanks for the help!:happy:
  2. zippy

    zippy Rockstar 100 Posts

    Hi Meekeene518, and welcome aboard.

    When you said the heater doesn't always blow hot air do you mean that the fan is intermittent or that the fan works, but the air isn't warmed?

    Suburbans have robust cooling systems, perhaps it takes yours some time to warm up enough for the heater to work. Do you have an extra low temp thermostat like the ones that come with chip sets?

    Back in the day, before environmental concerns and computer controls, it wasn't unusual to remove your thermostat during the summer months -- especially if your radiator was a little on the cruddy side. After summer, if you forget to replace it, the first cold snap was a rude reminder because your heater was just about useless.
  3. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    There is a vacuum operated control valve that controls coolant flow to the heater core. Where you've said it seems like a vacuum issue, that's the first thing I'd look at. Make sure the vacuum lines to the heater control valve aren't plugged/kinked and make sure the control valve is responding to vacuum.
  4. meenkeene518

    meenkeene518 New Member

    where is that located? i just have the haynes and i dont have a factory manual yet. the fan is not intermittent, just the heat is. since i have o=almost 200k miles i bet the vacuum line is rotted away. also where is that line located? Thanks for the help guys. also i replaced the thermastat and the coolant sensor, so those are not the issue.
    Last edited: Aug 23, 2008
  5. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    On my '98, the heater control valve is in the engine bay, passenger side, just below the AC accumulator and the air filter box.

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