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

[Waterloo]

(05-17-2019 )smorgan87 Wrote:  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

Nope, not a solenoid valve, they will burn out. You want that valve I posted, it only needs 9 volts, it opens the valve, wait four seconds, and shut off with the switch. A solenoid requires a constant power supply to stay open or closed, and if you forget to turn off, it can and will burn up. I have that same solenoid valve you linked to, and discovered that it is only good for 8 hours of continuous use and then it burns up. I discovered that after doing some research. The reason I went with the other valve.

[dhirocz]

I like this idea. I was considering this to help out my A/C during the hottest months. My A/C box doesnt bypass the core all the way when set on max cool, so it's marginal at best, even though the whole A/C just got overhauled. Definitely better than before though.

I was considering ball valves to shut off the core, one or two. I carry fittings to bypass if needed...I had to bypass a hose today as a matter of fact down by the APU outside of Mcdonough.

[Waterloo]

(05-17-2019 )dhirocz Wrote:  I like this idea. I was considering this to help out my A/C during the hottest months. My A/C box doesnt bypass the core all the way when set on max cool, so it's marginal at best, even though the whole A/C just got overhauled. Definitely better than before though.

I was considering ball valves to shut off the core, one or two. I carry fittings to bypass if needed...I had to bypass a hose today as a matter of fact down by the APU outside of Mcdonough.

Well, I just installed, so I have no clue on longevity, but I think it will be fine for a few years. It was only $26 and bolted right on, the switches, you can get at any auto parts store, I found some locally, but bought 5 or 6 on Amazon for the same price as one auto store switch. I will let everyone know how this works out, I think this will be fine in the long run.

[smorgan87]

Thats prty cool waterloo. I hadnt thought about the solonoids having a short duty cycle. That ball valve popped up on my amazin this morning. May have to try that one day. What all have u changed on ur ac system?

[Waterloo]

(05-18-2019 )smorgan87 Wrote:  Thats prty cool waterloo. I hadnt thought about the solonoids having a short duty cycle. That ball valve popped up on my amazin this morning. May have to try that one day. What all have u changed on ur ac system?

You had to ask, LOL! I hope you are sitting down... Here is my short rundown.

The one thing I did that made the system functional was to dig that ambient air temp sensor out from under the radiator and get it up into the fresh air up by the mirror. When that sensor was able to read a more correct temp, is when I was actually able to get cold air in the cab on a warm day. Prior to that, there was no cold air, or very sporadic.

There was also a TSB for a new harness to be installed at the blower motor, it has an inline resistor to tamp down the amperage needed to run the blower motor. It was not uncommon to replace the 30 amp fuse in the dash for the blower motor on a bi-weekly basis, as it simply melted in the fuse block. The new harness solved that issue, but the fan still overheats occasionally and has to be manually unplugged so that it resets itself. A real PIA. I still cannot run the blower motor on its highest setting, as it will burn up in the dash. I have installed close to a dozen blower motors that fried on me. Bench tested them all, dealer covered a few under warranty.

I've replaced the HVAC control module several times too, as they were failing left and right for some reason. I went through four or five of those, at $300 a pop. Warranty covered all but two.

I also went through ALL of the wiring associated with the HVAC system under the dash, if anything looked questionable it was replaced. The only thing I have yet to do is remove the entire HVAC box under the dash and hood to replace. I don't see a need for that this year. LOL.

No dye in the system either, just PAG oil and refrigerant. The dye in the system shuts it right down and it will not function. Been through that nightmare more than a few times, before I learned how to work on my AC system.

One thing I did discover is that the expansion valve needs to be an OEM unit, the aftermarket ones will not work properly with the AC compressor and the results are catastrophic. The compressor will fail. So only OEM expansion valves, the other parts, the dryer and what not, aftermarket is fine.

The high pressure switch is an item that fails on a regular basis, say every 18 months. The wiring is also very problematic to the switch, it looks like 18ga, and tends to break. I rewired that with some better wire.

Condensor up front, that has been replaced at least three times, I found that the OEM unit is the only one that fits properly, after market you are taking a chance. I have yet to see one that actually fits my truck, so I stick with the ungodly expensive OEM one.

I did just put new o rings in block going into the sleeper, found a leak, along with a new blower motor and resistor. The blower motor failed, it locked up for some reason.

As of today, the AC system works. When I installed that new ball valve, I drained the coolant system and made sure the valve was open prior to using a vacuum to refill. Everything seems to be working nicely. But we have yet to have a warm day here, so I probably will not know anything until next month.

Today, we are finishing up our new CB antenna install. I found an ingenious way to run that new coax into the cab from the mirror. I will post later, as I am sure some here will appreciate it. It is a much cleaner look than what most guys do when installing the proper antenna coax. The OEM cable fell apart in my hand at the connectors in the mirror, just shoddy quality and not reusable.

[smorgan87]

Youve legit had a rough go with ur ac system. I got sick of working on it in my 11 model and wired the compressor to a toggle switch and unplugged the thermisters so that tye compute would continue cycling the fan. Need to get a regular psi switch to cut it out on high psi and cycle the fan as well as cycle the compressor on the low side. Ive decided to eliminate the computer controlled blowers and run 12 or 14g thru a dimmer switch as that those blower speed controllers are what really heat up. Just gotta find the time to do it.

[earnies2]

I know this is an old post I was just wondering if it worked and how long it lasted?
Should I use 2 valves or is 1 sufficient

[smorgan87]

(05-18-2019 )earnies2 Wrote:  I know this is an old post I was just wondering if it worked and how long it lasted?
Should I use 2 valves or is 1 sufficient

Just 1 on the supply line is good.

[earnies2]

Thanks I will get that done do you have a wiring diagram?