Well howdy -

I have worked down the line of troubleshooting a low or no hot air through the climate control system - sans one more step. I'm hoping to get some input as to anything else I could/should check before removing the ENTIRETY of the climate control box. Here's the jist of it:

The Problem: Little to no "hot" air or luke warm even when turned up to full heat.

What I've done to test / troubleshoot:

• Changed / replaced climate control module. Control panel work appropriately.
• Flushed coolant system / replaced fluids. Backflushed the heater core both ways.
• I have no coolant leaks into the floor of my truck (no leaky heater core)
• Made sure no air bubble in system.
• Inflow and outflow to heater core lines are even temperature - both get around 165* when truck is a operating temp.
• Removed actuator for blend door - manually manipulated the door by hand. Seems to be sturdy and unbroken. Can pin and hold door full open, full closed - does not seem to be a broken blend door connection.
• No DTC's
• Recalibrate actuators / control module - full heat on control module does move blend door to full "heat" position. Likewise to cold.
• There is increased heat when putting the system in re-circ, but still not what you would expect.
• Using a laser thermometer, the output air on full heat is around *85. That may seem like a lot, but when you hold your hand...it feels luke warm at BEST and never really get 'hot' from the vents or inside the cab.

It seems to me like the blend door is good. Actuator is good. Heater core in/out flows are even, and would seem to me to mean the heater core is passing hot fluid through it and should be 'working'. Don't believe there are air bubbles in the system - i do not have big / quick temp changes in the system - and if there was an air bubble in the heater core, seems that in/out hoses would be different temperatures (and I flushed it as well).

Is there something I'm missing? Other than pulling the ENTIRE climate control system box out of the truck and inspecting for who knows what...I'm sorta at a loss. Anybody gone through all the above and found something that made sense? I've got all the dash apart for the most part to see/get at actuators...but haven't gone as far as disconnecting the entire deal and pulling it ALL out through the firewall and such. Is there something else obvious I should check for before going through the enormous PITA i'm sure pulling that whole thing out would be?

Thanks so much in advance for the replies....appreciate it...as does my bourbon balance at home (easier to fix = more bourbon to have for later). Cheers all!

Mike

 

Have you tried a new thermostat?

 

Heater lines should be around 200 degrees. You have a stuck thermostat. Gravy job compared to what you have already done!

 

Yup it's a lot easier than what he's already done

 

I replaced the thermostat as well. OEM specs, the 195* version I think? Was done prior to the post...forgot to add that part

 

I replaced the thermostat prior to the post. Figured while I was in it all might as well. Suppose I could have replaced the thermostat and had it been a bad one? But I did replace it....if that changes thoughts.

 

Yessir, already done. Suppose I could have replaced it and the new out of the box one was also bad? Always that chance...but they're cheap enough its probably not a terrible idea to try and replace with another one? I hate throwing good money at problems...I think finding the culprit...but for the ease and cost of another new thermostat...probably worth that effort...?

 

Skip the safety-stats. They ALWAYS fail almost immediately. Just get a good Stant thermostat, and it should help considerably.

 

I ordered up a Stant (actually 2 of them). Hopefully the answer is a thermostat that went bad, followed immediately by a 'new' thermostat that sucked or failed right out of the box. Changing those is easy squeezy compared to what I've already done....

Think I'll leave it apart until i get a consistent "it worked" or "didn't work" before I put access to the box away with putting the dash back....

keep ya posted!

 

I’ve done basically everything you’ve done as well (besides change the climate control module, which I doubt it’s that for my case) and I still get no heat. I had to change the stopping pin on the top blend door and I thought that was the issue, but still no heat. Seems like I get heat for like 2 seconds then goes back to luke warm. I kind of gave up for now since my ac is working great and summer is coming up. BUT still I definitely want to fix this also. I move my blend doors manually and it sounds like they both are working fine . I seen a video where you can look into the passenger floor vent (by the cup holder) with a flash light and “kind of” see inside your hvac box where the bottom blend door is at, I haven’t done this yet but I’m going to try just to see what I can see, maybe nothing but I’m willing give a look and to try anything besides removing the complete dash at this point