MBMB

The A/C system on our cars works by sending an electrical signal to a solenoid valve, which then draws vacuum on a vacuum unit to cause a mechanical effect.

Has anyone given any thought to replacing the vacuum units with digital servos and the solenoids with a board to convert the 12V DC to a square wave of the appropriate wavelength?

SeanR

Yes, had a dream just like that last night, but I was in an airlock......and someone was about to push the button to vac me.

blown 87

Most times the problems with the HVAC are going to be, low freon, bad pods, or a bad OAT sensor.

Fairly simple and once right, with new rubber parts they will last many, many years, not real sure how adding complexity is going to help much.

My $.02

MBMB

Hmm. I see it as simplification—taking the vacuum stage out of the electronic-vacuum-mechanical system.

blown 87

I can not see how doing a re-engineering of a HVAC system that works fairly well is going to be a simplification.

What I would like to see is a affordable speed sensitive upgrade to the Power Steering system.

the flyin' scotsman

Mark............I gave it quite a bit of thought using servos that are typicaly used in RC applications.........I fly helicopters.

As the system is electrical to the OEM solenoids its was thought that the RC servos could be mounted at the flaps (footwell, recirc, centre consel, water valve, defrost) with wiring run to them from the existing hvac harness. Then all hvac vacuum from inside the engine to the vac. distributor and onto the respective flaps could be deleted.

This design would leave the OEM hvac head as is as well the auto temp sensors.

What has yet to be engineered is the servo power required to open/close the flaps and the electrical power required to operate the servos.

I have spare RC servos that I could use to experiment when/if I get to hvac system.

MBMB

The electrical problem is trivial. When you get to the AC system, if you have some ideas on how to mount the servos, let me know.

Shark_Week

Malcolm, there are some pretty powerful titanium geared servos out there now, what would the power/torque requirements need to be?

JHowell37

I have to agree. I don't think people realize how common it is for cars to use this kind of setup. Virtually every car with automatic climate control uses a similar system. Why people think that something in a car that provides 15-20 years of reliable service is unreliable because it fails after 15 or 20 years, doesn't make much sense to me.

In the time it takes to go online and order servos that may or may not work, I could go out with a vacuum pump and see if the vacuum line that comes into the car is still good. Within another 30 minutes I could have the carpeted side cover removed and test the 4 or 5 separate circuits to see if they all operate when vacuum is applied.

If I find a leak in the line from the 4-way to the inside of the car, it takes maybe 10 minutes to replace with generic vacuum line available at any auto parts store. If any of the other lines leak it takes about 30 minutes to get the console out and replace them.

The dash can come out in under two hours if any of the vacuum diaphragms need replacement.