Heater

[merryworks]

Confusing situation here. Been troubleshooting my heater for the usual, air blowing colder than normal issue. Here is the situation.

2017 2500 with 6.4 V8

When the outside temp seems to get below 20F, my driver side air runs cold and passenger runs warm. All air runs to the proper vents so I believe my mix doors are running fine and my recirculation door does move fine. If I recirculate, the air tests to be a little warmer. Engine coolant runs between 185-215. I have yet to do a flush on the heater core since I am having a terrible time getting the hoses off and until the Minnesota winter breaks, I don't really have a hose I can do the flush with. I am still wondering if it is the heater core since when the outside air temp is about 30, the heat seems to work just fine. Any ideas would be appreciate or ideas on how to get those dang heater hoses loose. Thanks.

 

[crash68]

There have been several HD trucks reporting a similar problem, some were lucky enough to back flushing the heater core. Others like my buddy ended up having to replace the heater core to fix the issue.

 

[CheechDogg.0n37s]

You can also have a bad thermostat .... if the coolant doesn't go through the core can't produce heat ... did you check that out ...

 

[buckeyexx]

I’m in the same boat. Once it gets down below 30 or so it seems to struggle on my driver side. I’m going to try back flushing mine in the next couple of weeks

 

[merryworks]

Definitely going to flush the core first. I just need to wait until April so I can get a hose run. Too cold here to do it in the winter as my outside water faucets are all shut down for winter so they don't freeze and burst the pipes. Have thought about the thermostat but have not really researched it. Going to watch the temp the next few days. Thanks.

 

[buckeyexx]

I replaced my thermostat thinking it would help but it did not. That wasn’t the main reason for doing it but was hopeful it would take care of two issues at once. Mine was stuck open and not allowing the truck to get up to temp. If you do the thermostat I would go with oem because it’s not your typical stat. It has the housing,sensor and stat all in one. The thermostat alone is not replaceable. It was around 150.00 from dealer

 

[jws123]

Not sure why they keep clogging and doing this on 4th gen trucks some ppl very few have had good luck flushing the heater core but for the last 4 trucks ive worked on wound up replacing it to be honest its not that bad of a job if your mechanically inclined.

 

[kurek]

what on Earth would be in the coolant system to clog the heater core in just 4 or 5 years?

 

[Burla]

If you think it is a clog, rmi 25 would prove it either way. If it is clogged, rmi 25 would take the clog and deposit it into the over flow tank, I speak from experience, you would have gel like stuff in the over flow tank where it gets stuck until you remove it. Also, if you add rmi 25 and the over flow tank doesnt get gelled, you know the heater core isnt clogged, assuming it is getting flow. You need to determine flow first, if that is your issue that is what needs to be solved, if it is somehow gelled up, rmi 25 will take that slime out of your core.

I dunno though, drivers cold and passengers hot, doesnt sound like a clog to me, sounds like blend doors.

 

[Burla]

just curious so I googled it, this was from Cummins forum... response was from someone who treats this...

The heat is controlled by two elements, blend door and heater core. If you can change temperature, but just not get hot enough, the problem is likely with the heater core not getting hot enough. I'm including some information on common RAM heater core problems and solutions. The blend door issues are different depending on whether the truck is single or dual control. Either way, we can provide a solution to fix the doors. I'd also suggest checking the re-circ door for correct operation since that is a common fail and can affect temperature.


The RAM has issues with the heater core partially stopping up and having a temperature gradient across the core. Since the system is dual chamber, a difference in temperature across the core shows up as different heating characteristics on the two sides. Usually the driver will be cold and the passenger warm. The solution is an aggressive flush of the heater core and radiator system. Prestone makes a good DIY kit that you can find at Walmart.

It’s best if you disconnect the two heater hoses going into the firewall and flush backwards and forwards with a garden hose. Blow out the water and fill with the prestone chemicals and let it sit overnight. Flush again and it should significantly improve the heat. The more you work on it, the better it gets. You probably won’t get it back to 100% perfect, but you can get close. I’m enclosing a write up we did on the problem.

Another trick after flushing the core is to swap the heater hoses, making the heater core flow “backwards”. Not sure why this works, but we’ve had reports from customers that it makes a difference. Maybe it’s changing the flow characteristics in the core and making it spread the temperature across the face of the core better. We could probably figure it out with enough work, but if it helps, why question it….

 

[Matt Luken]

I have a similar issue. I noticed a drop in coolant first with some coolant smell periodically. I wasn't getting heat on either side when the reservoir was nearly empty. Filled it and burped the system. Repeated burp. Got some heat back on both sides. Also noticed that my temp was fluctuating between 185 and 212. Then driver side started getting cold. Passenger side warm. That's when I took it to the dealer. Diagnosis bad heater core. 2000 to replace, 2500 if they also replace the AC evaporator! Asked if back flushing would help. No. Not a warranty item. At this point I asked another garage, they didn't want to touch it.
Dealer says this is a common problem across FCA products. Huh?
I guess the extended warranty makes a little sense now. For 3000. Lol. AN FCA product too.
I am going to try the flush. Replacing the core is beyond what I want to try myself.
If it doesn't work they got me.
BTW I had all the service done at the dealer and at last oil change pointed out the coolant issue before I lost heat. My Inspection report said it was checked and was at normal level.
Obviously they didn't. I expect to get RAM Cares involved as I don't think I should pay 100% of this repair. On a 4 yr truck with 55k for mileage. Dealer also states that there is no blend door issue with this truck.

 

[farmerbrownmt]

I have 2 rams 2013 and 2019 with 5.7 standard engines and both with hot thermostats. The heat gauges on both do not get up to the 1/2 way mark even after driving 50 miles. When it is cold outside (o degrees or colder) neither pickup gets the cab warm enough to be comfortable. Dealer is no help they just say it's their nature. I' not a happy camper about the situation.

 

[GTyankee]

If you are a non smoker
just close the recirculation door
you don't need fresh air entering the cab all of the time

unless you just ate
Boston Beans

 

[merryworks]

Just a quick update. Finally got around to working on this. I spent about an hour working on getting the lines removed from the core so I could do a flush. Finally got the lines removed. Drained the core, poured in some CLR and let it sit for about 15 minutes, and then ran water in both directions through the core. Once clear, poured in some antifreeze to purge any water. Hooked the lines back up and it appears I have heat for now. Thanks for the help.