How to turn your heater core off and on in the cab.

[Waterloo]

This is an old topic... 2008 ProStar, CM-871... Notoriously ugly in regards to AC and Heat. I sorted out the pos International AC system, it finally works. Now, the other PIA issue with this archaic HVAC system, you have to crawl under the hood to get AC when it is hot, and heat when it is cold.

I'm in Michigan, it is 70+ during the day, and 40 at night. The AC in my ProStar runs continually, no way around it unless you want to go with an adrino and other such stuff that is out of my league.

Here is my solution... A ball valve with a simple on off motor on a DPDT switch. Not a selonoid, but a true shut off valve that opens and closes. Want AC, hit the switch up, the ball valve opens in 5 seconds, turn the switch off. Want HEAT, flip the switch down, wait 5 seconds and switch off. Easy peasy. No worries burning up the solenoid, because there isn't one!

I just wired it up, filled the system, tested it, and it works. Took a few hours, not a big deal, and am very happy!

I hope this helps someone.

Here are the parts I used...

The Dead Man Switch... https://amzn.to/2YyPFO3

The Ball Valve... https://amzn.to/2LMNUvr

I should be back to work next week, and we shall see how she holds up. The construction appeared solid, no clue on the board inside of the switch. It wired up easily, just follow the directions. And yes, you use all of the contacts on the underside of the switch, with two jumper cables. It was easy to do, not rocket science, just follow the included schematics.

Switch, the bright shiny one to the right...



The Ball Valve... The Blue Box...

[Lonestar10]

They do make electric valves for such occasions don't know name but it's similar to what you did only when factory installed as soon as you select AC it shuts then reopens if defrost or normal heat/vent is selected. My truck has a water spicket type valve but I can't use it due to apu so what you posted sounds simple enough to try.

[Rawze]

(05-15-2019 )Waterloo Wrote:  This is an old topic... 2008 ProStar, CM-871... Notoriously ugly in regards to AC and Heat. I sorted out the pos International AC system, it finally works. Now, the other PIA issue with this archaic HVAC system, you have to crawl under the hood to get AC when it is hot, and heat when it is cold.

I'm in Michigan, it is 70+ during the day, and 40 at night. The AC in my ProStar runs continually, no way around it unless you want to go with an adrino and other such stuff that is out of my league.

Here is my solution... A ball valve with a simple on off motor on a DPDT switch. Not a selonoid, but a true shut off valve that opens and closes. Want AC, hit the switch up, the ball valve opens in 5 seconds, turn the switch off. Want HEAT, flip the switch down, wait 5 seconds and switch off. Easy peasy. No worries burning up the solenoid, because there isn't one!

I just wired it up, filled the system, tested it, and it works. Took a few hours, not a big deal, and am very happy!

I hope this helps someone.

Here are the parts I used...

The Dead Man Switch... https://amzn.to/2YyPFO3

The Ball Valve... https://amzn.to/2LMNUvr

I should be back to work next week, and we shall see how she holds up. The construction appeared solid, no clue on the board inside of the switch. It wired up easily, just follow the directions. And yes, you use all of the contacts on the underside of the switch, with two jumper cables. It was easy to do, not rocket science, just follow the included schematics.

Switch, the bright shiny one to the right...



The Ball Valve... The Blue Box...

nice find there Mr. waterloo. Thanks for sharing.

[Waterloo]

(05-15-2019 )Lonestar10 Wrote:  They do make electric valves for such occasions don't know name but it's similar to what you did only when factory installed as soon as you select AC it shuts then reopens if defrost or normal heat/vent is selected. My truck has a water spicket type valve but I can't use it due to apu so what you posted sounds simple enough to try.

This is the first ruck I have owned that I have had to go under the hood to turn the heater core on and off. All of my other trucks blew ice cold air and heat year round without ever getting under there. This mess of a ProStar, well everyone knows what a garbage HVAC system these are.

Install was easy, everything bolted right up, no need to purchase anything extra, just drain off the coolant pull the spigot valve and replace with this motorized valve. It was an exact fit to what came out, 1/2" NPT.

Wired it up, insured it was working properly and installed switch in dash. Vacuum filled coolant, started truck, and I had heat! Flipped the switch, I had AC!

I spent less than $40 and my time.

I would use this over a solenoid valve. As the solenoid valves need to be babysat. They work with a constant draw of electricity to keep the valve open or closed, forget about it and the solenoid burns up, at least on the ones I have found.

With this unit, to open, flip switch to up to ON position, wait a few seconds and flip to OFF position. To close valve, flip switch DOWN to ON position, wait a few seconds and flip back to OFF position.

I would think as long as the quality of the switch and motor is decent, this should last a while. Finger's crossed.

[Lonestar10]

Well hookup dlogic to see if there is any codes for the blend door not working right my trucks only 2 years newer and my AC is plenty cold without having to heater core turned off But probably be even colder with it turned off.

[Waterloo]

(05-16-2019 )Lonestar10 Wrote:  Well hookup dlogic to see if there is any codes for the blend door not working right my trucks only 2 years newer and my AC is plenty cold without having to heater core turned off But probably be even colder with it turned off.

Yep, DL is the only way to diagnose, in all but one case. I won't bore you with everything that has been done to my AC system, the only original piece of it is the evap housing under the dash/hood and the lines running back to the sleeper, where the AC has always worked.

And I am religious on keeping a fresh filter in the intake box, along with climbing up there to inspect the blend door is functioning properly, and keeping the drip tubes clear. I even dug out the Ambient Air Temp Sensor from under the radiator and moved that up to the wiper cowl. That is what made a world of difference and actually got my AC system working, to the point I had ice cold air blowing in the front of the cab. I figured that out myself with the Bodybuilder schematics after spending too much time and money to get this system working.

DL will find the faults, all but that ambient air temp sensor, that was never on the radar, but solved 90% of my HVAC issues.

I was talking to my buddy out in Phoenix yesterday, he has the same issue with his 2008 ProStar and the heater core. I sent him the links to the valve and switch.

[DVT873]

Very nice. Dumb question. Are you shutting off both hoses or just one? I seem to remember 2 doing a little better job at keeping the heat away. Even one shutoff is a huge improvement.

[Waterloo]

(05-17-2019 )DVT873 Wrote:  Very nice. Dumb question. Are you shutting off both hoses or just one? I seem to remember 2 doing a little better job at keeping the heat away. Even one shutoff is a huge improvement.

Just the inlet side.

[smorgan87]

I think what u want is a 12v solonoid valve.
HFS 110v Ac or 12v Dc Electric Solenoid Valve Water Air 1/4", 1/2", 3/4", 1" NPT Available (12V DC 1/2" NPT) https://amzn.to/2Q9gl5f