chucks86

Hi everyone , I have a 1998.5 24v dodge 2500 that I have been fighting poor heat for years best it gets is 100-110 out the vents on the 2nd or 3rd position on the blower with climate temps around 25 to 32 degrees if I put it on the 4th setting it almost cools the coolant . What I have done so far , I have replaced the t stat with a 190 mishimoto high temp . That did little to no help . So at that time I replaced the heater core and when I had it out I looked at the vent that operates the temp door to make sure it goes from one side to the other and it did . After I got that heater core in I drove it 60 miles and still had that same poor heat . I put my temp gun on the heater core top with the glove box still removed and it was at 98 to 100 degrees . I checked the temp on the head and found that it was 170 . So at that time I put card board in front of the rad 100% blocking off air flow . I drove it the next day same 60miles and got the same poor heat and head temp was 190 -180 degrees. I thought maybe my clutch fan was locking up at higher rpm speeds so I removed it completely and have the rad half way blocked off. The temps for the last 60 miles with all that done was 100-115 dregrees out that vents and 205 degrees on the head and 195 at the t stat . I'm starting to wonder if 100 to 115 degrees heat out the vents is normal . I love this truck it never has let me down , in the summer it gets 18 mpg and I have got 85hp injectors , atc exhaust manifold , 4 inch exhaust , Volant intake , banks big horn intake . I'm just confused at this point and wanting to see if im the only one with this issues after I have done all this work. I have been a lurker for this form for years just never had that need to post till now . Thanks

texasprd

Pull your blower motor and check the fins on the AC evaporator core to be sure they aren't plugged with "compost". The blower blows through the AC core first, and if it is blocked you'll have poor airflow and probably poor heat.

What reading do you get if you put your IR gun on the inlet and outlet heater hoses?

Does changing the blower setting have any noticeable effect on airflow or blower noise in the first three settings? Are you sure the blower speed is changing as you move the switch? If not, then you may have a bad resistor.

chucks86

I will take the blower out maybe tonight , the lines read 150s to 170s and the heater core can get to 140s but poor heat . The blower makes noticeable air flow on different speeds . The one thing I have noticed is that the lower speed it gets warmer , for me to hit the 100 - 115 it had to be on speed 2 . How hot does the heater get on yours if you can test it . I would like to see 130 I know that there will be a slight difference in engine temp compared to heater vent temp . Thanks for the reply .

KATOOM

I'll have to check the exact temperatures on mine again with the laser temp tool. But I do know that ever since I replaced my heater core years ago the heater is nice and HOT... I never run it much hotter than 1/2 to 3/4 on the temp dial otherwise it runs you out of the cab.
It sounds like either your blend door isnt working as good as you think it is or there's very little air flow due to a possible blocked upwind evaporator in the HVAC box.

Rare1

When you call for heat, does your AC stay on? With heater hoses 150-170 the heater output should easily be 130 unless you are cooling the air also.