Colder A/C in under 25 min?????

[DennyDay]

Did this fix this spring on my 06 Mega when I was getting ready for a Texas summer - - - simple, caused no problems, worked as written. Left it turned of except when I serviced the truck (twice) then turned it on to let water flow for the rest of the day, then turned it off again. Made the AC work a little better. - - No make that alt better!

 

[CBlack]

Has anyone done this to their 6.7?

 

[mwilson]

Has anyone done this to their 6.7?

If I had one I would centainly try it....

Why don't you try pinching the heater line closed and then use a thermal gun to check the flow in and out of the turbo??? That would tell you if my theory is right or not.

Thanks for finding this thread BTW, I thought that I had gone through this before.

Mike.

 

[AH64ID]

If you tow or use more hp than stock on a regular basis I would NOT block the flow from the head. You need to have a bypass valve. The flow, even when not heating, helps keep the rear cylinders cool and pressure down. Blowing our the rear freeze plugs is a real issue on these trucks.

Personally even in 110° weather I have never even considered complaining about the a/c in my 05.

 

[CBlack]

If you tow or use more hp than stock on a regular basis I would NOT block the flow from the head. You need to have a bypass valve. The flow, even when not heating, helps keep the rear cylinders cool and pressure down. Blowing our the rear freeze plugs is a real issue on these trucks.

Personally even in 110° weather I have never even considered complaining about the a/c in my 05.

Come ride in my 08 when it's 90+ outside and you will!

 

[MLee]

As long as I've been here I have never seen this idea. I am always looking for more efficiency and improvement. Thanks again.

 

[AH64ID]

Come ride in my 08 when it's 90+ outside and you will!

I wonder what the differences are?

My 05 is ice cold in 100°+, as is my dad's 06, and my friends 07 6.7.

 

[CBlack]

I wonder what the differences are?

My 05 is ice cold in 100°+, as is my dad's 06, and my friends 07 6.7.

Not sure. I'm going to pick up a thermo today to stick in the vent. When the compressor was replaced everything was within spec. It's slightly better now but not markedly so. I have a co-worker with a 08 Megacab and he has the same issue.

 

[CBlack]

The PDF in the following link has a diagram that he used on a 6.7. I asked and he doesn't have the valve in yet, just the bypass hose and it worked quite well.

http://www.cumminsforum.com/forum/13020922-post9.html

 

[JR]

Humidity plays a big role in how well an a/c system works. Pretty sticky down in CBlacks neck of the woods.

 

[gtobey]

Irregardless of the engine model or type, I did not want to block the coolant flow through the heater core back to the cylinder head. I just wanted to "divert" that flow from the heater core inside the A/C box back to the head from the water pump, thus not re-engineering the coolant flow, but having an electrically operated "bypass" valve. This is the 2nd summer of operation, and so far it has been flawless.

The real beauty of this valve is that you can control it from inside the cab, instead of having to get out and turn the valve. It has been very handy to have the control switch in the cab when a day is cloudy, a slight drizzly, and just a bit cooler, to be able to add a little coolant flow to the heater core so as to add a bit of heat in to the A/C as needed. I can keep rolling down the interstate, flip the switch, and enjoy air of the right temperature. Then, if it gets blisteringly hot again, another flip of the switch and I'm back to maximum cooling to quickly bring the temps down in the Megacab. Since a very little bit of coolant will always flow through the core, there is no danger of damage to the core, and no danger to the cylinder head as it always gets the coolant flow.

The temperature from the center ducts with the A/C on Max cooling/high fan has consistently been 34-36 degrees when driving down the road when the hot engine coolant is bypassing the heater core. When idling in traffic, the temperature from the vents will increase about 3-4 degrees, because less air is moving over the condenser core. You can tell when the condenser core reaches the preset temperature point which requires more airflow, because you will hear the engine cooling fan engage and spin faster until the temperature of the air coming into the fan is a bit cooler, and the fan speed drops. I do not hear the roar of the fan speed increasing when driving at interstate speeds.

This simple system of an electrically operated coolant bypass valve has worked, and continues to work, for me. I am glad I figured it out when I had the entire dash out having to repair the mode doors and axles.

 

[MLee]

How about an RV bypass valve? (used in the water heater by pass system) there is a single or a three way that could be installed.

 

[gtobey]

Here's what I used. Works great. Got it directly from Thermotion. http://www.thermotion.com/topic/18-electronic-coolant-control-valve.aspx

 

[Motorhead]

Here's what I used. Works great. Got it directly from Thermotion. http://www.thermotion.com/topic/18-electronic-coolant-control-valve.aspx

Now THAT is SWEET! What do they cost???

 

[JHumphries]

Just because I like to dream, has anyone thought about using the factory temperature control to control the 4 way valve?

 

[gtobey]

Thought about it, and according to Thermotion, it can replace the blend doors by doing so. Visit their website and check out the schematic for the wiring. I'm sure you could make it work the way you want with help from them.

I just wanted an on - off type of setup, however, I used the same type of valve that can be variably controlled. I just power it until it is fully one way or the other, then use the dash controls normally if I need heat. The best thing is that I don't have to get out to open or close the valve to turn off the coolant to the heater core. That's worth the cost of the valve to me.

 

[glenalt]

Nice mod, thanks. Glen

 

[CBlack]

Bringing this back up since I just had to replace my entire AC system and it still sucks.

A guy on another forum with the same model truck as mine did this...

The valve he used was this one: Model: 4373K54 from here: http://www.mcmaster.com/#three-way-ball-valves/=13p3q22

I'm having trouble imagining the flow through the valve based upon the flow directions shown on the valve description. The gent who posted it originally said it works but it seems like it'd still flow some into the heater core.

Thinking I'm going to try it out.

 

[Blakers]

I believe the flow is FROM the cylinder head. Wouldn't it be better to put the diverter valve there? Unless two valves are used, wouldn't there be a chance that warm water could rise from a lower point and displace the cooler water in the heater core, thus putting some heat into the core? Is a diverter valve even necessary? Why not just install a ball valve that would block the flow completely? It would be like plugging that port on the head as if the engine was used in a tractor or industrial application where no heater was desired.

 

[CBlack]

Talking to my BIL who has a Peterbilt, I opted to to take two of the valves I listed with a 90 degree bend on each. When the valve is closed one way, coolant will flow through the heater core and make the full loop as normal. When closed the other way, it will bypass the heater core but otherwise stay the same.