In the two previous 99 Dodge Cummins 2500 4x4 pickups that I had, once I replaced the heater core, evaporator core, cleaned the hvac box, new 190* thermostat, new blower fan motor, both of those pickups would roast me out of the cab if I ran the heater on high for too long.

 

On this 01 Cummins 4x4, it has a new radiator, new water pump, new heater and evaporator cores, cleaned the hvac box, new heatertreater transposer for the temp blend door, new blower motor rheostat, and new NAPA 190* thermostat. The only thing that I haven't changed is the heater blower motor on this pickup, but I have good airflow and my engine temp is running 190*, but this truck will not roast me out when it gets too cold outside. I just installed a geno's garage winter grille cover over the radiator, condenser, and intercooler, but that didn't make it do anything different and the truck still runs at 190*.

 

Anyone have any other ideas to fix this issue?  I know this is a very common issue in the 2nd gen dodge pickups and hopefully someone has some ideas as what to do next to fix it.

 

Thanks!

 

Doug

 

 Thanks @IBMobile, I may have some stainless screen in the garage. I'm sure that would work just as well.

 I also want to use some of that same screen for a bug sreen behind the grill come summer time.

2 hours ago, Doubletrouble said:

I may have some stainless screen in the garage.

Metal screening would be a little hard to glue to the cowl.  To affix that type of screening I would use sheet metal screws with flat washers and a sealant on the screw holes to stop any future rust.

3 hours ago, IBMobile said:

I used nylon window screen mesh that I had lying around.  The adhesive, I think I used, was clear silicone sealant.

His girlfriends taught him all about Silicone.

2 hours ago, JAG1 said:

His girlfriends taught him all about Silicone.

She kept slip-sliding away.  Just couldn't hang on to her.

Amazing the number of subjects temp differences between trucks can lead to. Sounds like my history class in high school. Oh well... life is wonderful and at my age you become wiser about the circumstances you place yourself.

 

Can't wait to hit the mountains with IBMobile and his gang.

Biggest thing for heater performance is good flush and fill schedule of the coolant. Do n9t try to run to the max limit of any coolant. Don't believe any 100k or 150k life span. I typically change around 75k. If you wait too long the pH level will already eating the metals of the heater core and transferring the oxides of those metal to the cooler side as scale blooms. 

I haven't drove my Cummins much since redoing the head gasket again this last spring/summer, because I ride my Harley when the weather is nice. 

 

Lately since it's colder now, I noticed that my Napa 190* t-stat tends to bounce around in temp while driving down the road. It will be at 190-195* and then sometimes I see it drop down to 183*. I'm used to a t-stat staying at the temperature that it's rated for, so I don't know if this is an issue or not.

 

I still need to test the blend door yet for full travel of hot and cold. I did time the blend door actuator when I installed the heater treater, but I might just buy a new actuator and install it.

Normal. Mine drops to 186°F the cycles up to 192°F and opens then drops again. Good sign to do a winter front. Colder is not efficient, being coolant starts dropping more energy is attracted to the cold. Myself I'm going to install a 200°F thermostat (4th Gen) here soon. Hotter coolant has better thermal efficiency.

 With the temperature fluctuations here this time of year I don't know if a 200° would be good or not. We sometimes see 40-45° swings here this time of year. It was nearly 80 two days ago, tonight's low is 36.

Maybe you should ask @pepsi71ocean he's been running a 200*F thermostat year round. He's over there on the East Side of the US.

Just got back from a 2 week trip on my new coolant and a Murray Ultra Thermostat. It cost more and looked different but the person at the O'Reilly's counter told me,  well, here is a discount for you so you just try it out. Bring it back for a refund if you don't like it. Every time I looked at the temp gauge it was a steady 190 or so. I guess well enough then.

 

I didn't like the name 'Murray' because Murry Bicycles when I was a kid was a pain in the rear bike to own but, I think it's a different company and spelled different too.

Update, but it's with my lifted and TRD supercharged 3.4 5 speed 97 SR5 4x4 4Runner, which was having only warm air despite having a brand new heater core. On max fan speed and full hot on the temp control, the highest temp was 129°.

 

I just flushed the heater core by itself with CLR, letting it set in the core for 1.5 hrs. I blew the core out with compressed air. I filled the heater core twice with water and blowing that out with air until nothing but clean water came out.  Now on full heat and max fan speed, I get 165° heat coming out.

 

Now I'm doing the same process with my Dodge tonight. I might just do the process twice on it for good measure.

My Dodge heater core had some debris in it, but the coolant is fresh and clear from redoing the Cometic MLX head gasket and head studs less than 5k miles ago. 

 

I flushed it and ran CLR through it 3 times (2hr soak the 1st time), and then kept flushing it both directions between the supply and return lines until there were no more debris coming out.

 

Then I did the poor man's toe-in measurement of the 4th gen steering linkage. 

 

I have yet to install my brand new adjustable control arms and my Thuren front coil springs before getting it aligned again.

 

As soon as I can get it fired up again, I'll post the results of the temps.

 

In the FSM, in the heating & air conditioning section on page 24-7 it talks about a diode that might need to be replaced.

 

What is it for and where at in the wiring harness is it located?

9 hours ago, 01_Cummins_4x4 said:

In the FSM, in the heating & air conditioning section on page 24-7 it talks about a diode that might need to be replaced.

 

What is it for and where at in the wiring harness is it located?

No idea, it's not shown in the FSN section 8W-42 AIR CONDITIONING-HEATER. 

"The DIode" must be like "The Surgeon General".  It's just there, somewhere. 

 

- John

Never seen any diode in the electrical of any Dodge as of yet. But even then that would only affect the electrical of a device but will not have any effect on the coolant flow or heat production of the HVAC system. Be aware the only way to clean a heater core completely requires the removal of the heater core and opening of the tank heads running a stainless steel rod through all the core tubes and soldering closed again. Yes, I've done this in the past with old brass heater cores but with aluminum cores, you are not going to be able to do this trick like I did in the 70's and 80's. 

I know that to truly clean a heater core or radiator is via the rod method, but this coolant has less than 1k miles on it. This coolant still looks new, no cloudiness, not dirty looking. 

 

I haven't ever done a coolant flush on this pickup, just a drain and refill. There must have been some residual debris that fell into the coolant ports of the block when I was changing the head gasket the last time. I should've just done a coolant flush then after redoing the head gasket.

Color means nothing. Being coolant could look fresh out of the bottle and have a pH of less than 5.0 and oxidized metals that settled in the bottom of the block. Now on high Rev operation those solids could be pushed into the core tubes of the heater core and radiator. Then the only way to clean this up is rodding out the heater core and radiator. This is even possible with distilled water being used.

I finally got my new adjustable control arms and Thuren front lift springs installed. I removed the front lift spacers to get a smoother ride out of the front suspension. 

 

I was able to drive it and when it's fully warmed up, I'm getting 150° temp out the dash vents on full heat and highest fan setting. That's like 50° hotter than it was before.

6 hours ago, 01_Cummins_4x4 said:

I'm getting 150° temp out the dash vents on full heat and highest fan setting. That's like 50° hotter than it was before.

 

I think you won.

 

- John