I've got a 1997 Suburban and would love a complete list of items to troubleshoot a heater that doesn't work.

What I've checked/done so far:

  • blower motor is OK
  • can switch from defrost/feet/face
  • there's coolant in the system - had to replace some hose, and there was a broken 45 degree heater hose connector that I replaced. There's still a small coolant leak past that - probably on the hose that goes to the rear heater (I can't seem to find a replacement online for that)
  • both front/rear blows cold
  • the vacuum hose from the heater valve is pulling a vacuum, but not sure how to test the valve itself

How can I check the heater valve, and what else should I check to rule in/out problems with the heating system?

  • Are the heater hoses getting hot? There should be two hoses coming from the right side (passenger) of the engine (one from the intake manifold the other from the pump) and goes to the firewall on the same side. Check them for heat at the firewall. Feb 3, 2021 at 18:45


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