Need Heat Help

[TMyers]

2013 CTD
EVIC gauge shows the truck at 188 to 192 degrees when warm.
With the heat full on, dash (face) vents selected, when I turn the fan on high, I get a burst of Good Hot air from the vents.
After about 10 seconds, the air goes to lukewarm at best. If I turn the fan back off and wait about 30 seconds then turning it back on to high, I get the burst of Hot air again, then lukewarm.

I would greatly appreciate any advice.

 

[crash68]

sounds like the coolant flowing through the heater core is reduced/restricted. Check the heater hoses, if the leaving is significantly cooler than the entering, it's a flow or restriction issue. If not it's probably one of the blend doors.
I think it was the '13-'14 CTDs that had a water pump recall.

 

[TMyers]

sounds like the coolant flowing through the heater core is reduced/restricted. Check the heater hoses, if the leaving is significantly cooler than the entering, it's a flow or restriction issue. If not it's probably one of the blend doors.
I think it was the '13-'14 CTDs that had a water pump recall.

I had the water pump recall done a couple years ago. I've got the hood up now looking at flushing the heater core.

 

[crash68]

If your going to be draining the coolant down, now would be the time to replace the thermostat.
I believe your truck still uses HOAT coolant. If you don't buy premixed to refill the system, be sure to use distilled or deionized water to mix with the coolant.

 

[68PowerWagon]

If your going to be draining the coolant down, now would be the time to replace the thermostat.
I believe your truck still uses HOAT coolant. If you don't buy premixed to refill the system, be sure to use distilled or deionized water to mix with the coolant.

I have seen this before "distilled or deionized" water. Why is this? Why can't you use regular tap water?

 

[TMyers]

Update: I HAVE HEAT!!!!!
I flushed the Heater Core with water hose and air.

I did the flush both directions, several times. After flushing, I poured distilled water into the hose until it filled the heater core then blew it out. I did this 3 or 4 times to rid the core of regular water.

If I were going to do it again, I'd buy new clamps. The squeeze clamps are junk.

I literally have to turn my heat down now.

 

[68PowerWagon]

Update: I HAVE HEAT!!!!!
I flushed the Heater Core with water hose and air.
I will add pictures later.

I flushed my system & it didn't work. I think I need to do as you did & just focus on the heater core itself.

 

[crash68]

I have seen this before "distilled or deionized" water. Why is this? Why can't you use regular tap water?

The minerals and chemicals found in tap water can form deposits within the cooling system.