I read this on another forum so I tried it this morning, and it appears to work great! Simple mod of installing a shutoff valve on the heater core line coming from the engine head.

I always noticed my AC performance is great when the engine is cold, but once the heater core gets heat soaked the performance decreases. Now even with the engine hot the AC gets cold fast after startup.

MikeyB

 

do you have a link to the thread, or more specific instructions? thanks.

 

The Dodge Talk forum is down right now for upgrades, but once it's back up I'll link it.

MikeyB

 

good deal. i appreciate it.

 

Can you post some pics? i have been thinking about doing this but wasn't sure if had to route the coolant somewhere else or just shut it off with a valve.

 

Can you just valve the supply line off?? or do you have to bypass around it to keep the water flowing?

Rick

 

This has been the norm for big rigs for years. My Pete AC sucked til i turned the water off. They don't have a bypass set up, just shuts water off. Go to Home Depot and get a ball valve and 3/4" in/out nipples and cut your rubber line.

 

Would love to see this written up step by step as a DIY. I would like to do this to mine. cbrahs, have you done this to your Mega??

 

I used a Factory Air shutoff valve P/N 84707 from Advance Auto Parts.

Locate the heater hose running from the engine head (look for the vertical nipple screwed into the head above the turbo and next to the valve cover) to the heater core.
Cut the heater hose (good location is right under the windshield cowl) and installing the valve with hose clamps for 1-1.25" heater hose.

MikeyB

 

Probably stupid question but doesn't this keep the water from circulating? I understand blocking off the heater core but how does the hot water get back to the radiator?

 

The cooling system doesn't require having a heater core installed. Just taps into one of the coolant ports in the head and returns back to the pump.

MikeyB

 

When you have your heater turned off it has it's own valve to stop the water from circulating through the heater core. If your mod works then it means the stock heater valve is letting some amount of hot water through the system.

If you have ever broken a heater hose or your heater core started to leak you could have just pulled the hose off and put a plug in it this is the same thing except a valve.

Great idea.

 

Cool! I think I will try it. How many degree drop would you say?

 

From the shop manual our trucks constantly flow coolant through the heater core with no shut off valve. The blend door controls amount of heat that enters the HVAC system.

I don't have a AC thermometer so no numbers for the before and after. But on the other forum the owner did measure and I think he said with the valve off the AC temp is down to 40-42 degrees at the registers. The Dodge Talk forum is still down but once it's up I'll verify.
But to me the air does seem colder coming out of the vent registers than before.

Here's a pic of my setup.



MikeyB

 

This sounds like it is at least worth trying. I do not like my AC on the really hot days ecspecially if sitting in traffic and not getting good flow over the radiator.

I will be trying this soon... Looking forward tot he Dodge Talk link

Thanks