I have been posting pics and results along with members of another forum. I wanted to start it here so you all can see what is being done.

It has been old hat with big rigs for many years to shut off the water flow to the heater core during hotter months. This eliminates heat conductivity into the AC system and creates a colder temp coming out of the vents.

I went to Home Depot and purchased the following parts

2- 1/2" brass quarter turn ball valves
4- 1/2" to 5/8" nipples

had the 4 hose clamps in the shop

I have been wanting a hose cutter to make straight cuts for a long time. Just ended up buying one while I was there. Going to do the mod as soon as the thing cools down. had to drive it to Home Depot since it was raining out.



Here is a pic of the parts installed



went to the dealership and showed my service adviser. He thought it was a cool mod and was curious to see the temps.

82 Degrees out
AC on high recirc
in their parking lot no moving



So far so good, no leaks and the AC temp is cooler. I will get some more temp readings when it gets hotter out and also turn the water back on and get some readings as well.

The 6.7 guys will have to get some "T" fittings to actually bypass the water from the pressure side to the return side since the turbo has coolant flowing thru it.

 

That's a good idear. I would bet that dropped the vent temp close to 10 degrees.

 

from results from other guys that have done it, they are reporting 8-11 degree drop. Just have to remember to open the valves now and again to circulate coolant so it does not deteriorate inside the heater core.

 

So for us Dummies in the audience, I know you said it makes the AC run colder but explain a little background here.

 

without the heater core heating up by the coolant, it will allow the a/c to provide cooler air thru the vents. You won't have any heat being transfered into the AC box. just cold nipplish air!

 

When blocking off the heater core you will not have any fluid flow coming from the waterpump. I know on LS1's you have to have some flow from the inlet and outlet of the waterpump to allow the thermostat to work properly. I like this idea and am surprised more people have not come up with this idea. While you are modifying your coolant system, a coolant filtration system would be advised to help your coolant system live longer.

 

coolant filter is next for me. Going to use a CAT coolant filter since it has the conditioning chemicals in it already.

the good thing is that the Cummins heater supply does not come straight form the water pump but rather at the back of the head.

 

Just for grins the other day, I shot the inside of my A/C vent with a laser temp probe I borrowed from a friend. Conditions were very similar to what you described...mid 80s outside, A/C on max recirculate, truck sitting still and the temp at the vent showed to be in the low 40s. I'd be curious to see if that makes any difference on my 6.7. As hot as it gets here in the summer, I need all the help I can get.
Thanks for posting that Chris.
Jim

 

He no problem guys/gals. My truck is at the dealer today getting right tie rod replaced due to a torn boot. my tech is going to open the valves and get another reading as if the mod had not been done. he is going to shoot a pic with his phone so i can post it here. he is cool and the owner of the greasy aresed fingers in the pic! LOL

 

Post fixed..