Jump to content
  • Welcome To Mopar1973Man.Com LLC

    We are a privately owned support forum for the Dodge Ram Cummins Diesels. All information is free to read for everyone. To interact or ask questions you must have a subscription plan to enable all other features beyond reading. Please go over to the Subscription Page and pick out a plan that fits you best. At any time you wish to cancel the subscription please go back over to the Subscription Page and hit the Cancel button and your subscription will be stopped. All subscriptions are auto-renewing. 

Recommended Posts

It blows hot on low, when I turn it up any higher it blows cold.  New 190 thermostat, and AC works perfect.  My truck has the manual cable to the door and it appears to be opening and closing as it should. 

 

Both heater hoses are hot, from what I read this is an indication of a blocked core.

 

Am I missing something?

Link to comment
Share on other sites

Something to consider when feeling the heater hoses is if the temp going in is 190* and the heater pulls 20* from the coolant the output is 170*. It is a little hard to feel the difference with your hand because either is so hot. Before repairing mine I had warm air with the temp control on high and anything less than that it was cold. My core was leaking slightly and when I remove it, it was plugged externally with trash. The all hot or cold is usually a blend door problem from what I know, but I am not familiar with a cable operated one. Mine has a DC motor for the blend door and the fitting between the two had broken and the door was improperly indexed. The AC worked fine but the heater did not. Is it possible the cable has slipped?

Link to comment
Share on other sites

I thought it was the blend door, because both heater hoses were hot.  then I looked under the box and couldn't find the motor.  Then I took off the glove box and I can see and feel the cable moving full rotation with the heater control.  I wasn't able to move the level any more than what the heater control did...(meaning it seemed tight).

 

Then I read Mike said if both lines feel about the same heat then the core is most likely bad.  

 

I will let you know what it is.  I think I will try to fix the heat before the oil leak.

Link to comment
Share on other sites

I thought it was the blend door, because both heater hoses were hot.  then I looked under the box and couldn't find the motor.  Then I took off the glove box and I can see and feel the cable moving full rotation with the heater control.  I wasn't able to move the level any more than what the heater control did...(meaning it seemed tight).

 

Then I read Mike said if both lines feel about the same heat then the core is most likely bad.  

 

I will let you know what it is.  I think I will try to fix the heat before the oil leak.

 

I was talking to Mike a little while ago and he confirmed what you are saying as far as the cable. I have never had to mess with one in a second gen.

Link to comment
Share on other sites

If you can't install a new one right away and you are needing heat you can try flushing the core out backwards. I did that with mine to get me through the winter. Some gunk came out when I blew it out with the garden hose. Plenty of heat now in 0-15 deg conditions

Edited by TFaoro
Link to comment
Share on other sites

  • Owner

Something to consider when feeling the heater hoses is if the temp going in is 190* and the heater pulls 20* from the coolant the output is 170*. It is a little hard to feel the difference with your hand because either is so hot. Before repairing mine I had warm air with the temp control on high and anything less than that it was cold. My core was leaking slightly and when I remove it, it was plugged externally with trash. The all hot or cold is usually a blend door problem from what I know, but I am not familiar with a cable operated one. Mine has a DC motor for the blend door and the fitting between the two had broken and the door was improperly indexed. The AC worked fine but the heater did not. Is it possible the cable has slipped?

 

When I last checked mine this winter on about 0*F day. The hose from the head was so darn hot you can't hold the hose for any length of time. But now the return hose the one that goes to the tube under the exhaust that one is so much cooler its a perfect hand warmer temperature. Last time I measure the vents temperature I was blowing about 160*F from the center vents on high fan. So my return hose is much cooler because of the heavy exchange of heat.

Link to comment
Share on other sites

Your only puts out that much heat because your truck your brain might freeze. :cookoo:  All kidding aside, mine is not that hot, not sure why. I only see about 140 on mine. Still enough to keep me very warm. Much much better than before the change.

Link to comment
Share on other sites

Update on the heater core.  Pulled it out this weekend and replaced it - not too bad of a job. Actually much easier than I thought, & Mike's article/video helped out. 

 

Replacing the dash sucks.  The little screws for the vents were a pia, but the dash looks nice and my heater blows nice and hot now.

 

Next up is the oil leak - maybe next week or the week after?

  • Like 1
Link to comment
Share on other sites

×
×
  • Create New...