Hevac Havoc

gencybay · Nov 18, 2017

It was rather nice having icy blasts from the dash during the summer. Not so nice now.

RHS blend fault. I can't see me getting round to doing that for a while.

In the meantime, will the fan throw a hissy fit if I cover the pollen filter aperture with gaffer tape?

TY

brianp38dse · Nov 18, 2017

Would it not work in manual mode and recirculating.

gencybay · Nov 18, 2017

brianp38dse said:
Would it not work in manual mode and recirculating.

That's what I've tried over the past few days. It still blasts cold.

brianp38dse · Nov 18, 2017

That's me out of ideas then

others may know more.

biketeacherdave · Nov 18, 2017

I Dont see why it would. Mind you iv got my heated seats on and hevac set to 26 collecting me dinner

Grrrrrr · Nov 18, 2017

Can you move it with the Nanocom or recalibrate?

The Mad Hat Man · Nov 18, 2017

https://www.gov.uk/check-if-a-vehicle-has-been-recalled

gencybay · Nov 18, 2017

Grrrrrr said:
Can you move it with the Nanocom or recalibrate?

Nanocom reports RH blend motor short.

I'll have to get it all out in due course. Just don't feel like doing it at the moment. Also, as family chauffeur with one member working shifts and weekends, it really a daily driver.

dubbleRR · Nov 19, 2017

What i did when the passenger blend stuck was a 19 /20mm long socket on the end o my finger ,This was on the left motor moved the glove box down a bit and using the socket like a wee hammer managed to tap the blend motor . You need to stop n start the ignition switch and click heat up n down,till the wee book goes out.There is other ways im sure ,but gently tapping the motor in this way worked for me

2 or 3 years now,

martyuk · Nov 19, 2017

Pull the HEVAC unit out (it's a few trim panels and screws etc)

Unplug the blend motor connector from the HEVAC controller, and then find the Brown/Black wires from the blend motor with the BLUE tape on the wire (assuming they are still color coded!)
With a couple of thin bits of wire to poke in the end of the connector, and a 9V battery (or 12V power source) connect the battery up and it should move the motor. Swapping the polarity will make the motor run in each direction - so just manually drive it until it's at the other end of it's travel, and it should be at full hot.

If you want to make sure the HEVAC won't try to drive it again, then either cut one of the wires, so it can't try to drive the motor - or pop the pins out of the connector housing by lifting the rear locking tab on the housing, and then using a small jewellers screwdriver, or a needle etc in on top of the pin from the front to lift the locking tab on the pin itself, and then pull the wire out the back of the connector.

Replug the connector to HEVAC and refit.... warm air should be the result until you can get around to changing the blend motor.

Mukiwa · Nov 24, 2017

Thanks for that info Marty. I had to do my passenger blend motor (SWMBO's throne

) All my blend motors move under 9v power but when hooked up to the HEVAC they don't or maybe they do and then they don't again.
Anyway I read today somewhere that if you put your temp to mid 20's (I put mine to 21c) then the blend motors play nicely on start up. It worked!
Bizarre bloody car.
Hoppy

martyuk · Nov 25, 2017

The HEVAC system, whilst fair simply in theory as to how it works, is a pain in the butt.
If your motors are OK, then the issue could be the feedback potentiometers in the blend motors themselves.. If the HEVAC tried to drive the motor, but doesn't see a response from the feedback pot in the correct direction (eg a bad piece of track on the pot) then it will flag up the error and then just stop trying to drive the motor until the power is cycled.

Moving the temperatures might make a difference as depending on the air temps, on power up the HEVAC probably moves the motor straight away and the feedback pot will move off the bad piece of track and return a proper reading again. Until the next time if stops/goes slowly over the bad piece and the HEVAC detects it and shuts it down again.

As I say, the theory in the HEVAC control is good, but all it does take is for one little thing like that to cause it to stop playing ball!

pwood999 · Nov 27, 2017

Remember there's multiple temperature & other inputs to the HEVAC. If any of them are wrong it affects how & if the controller moves the flaps.

Water Temp - measured on heater core pipes (connector often corrodes causing errors)
Evaporator sensor - probe in back right of heater box. (connector also corrodes)
Aspirator - either full of fluff or fan motor not working
Sun Sensor - supposed to compensate for warm sun !!
Road Speed - dunno why the HEVAC needs this ??

Check & clean the contacts on Water Temp & Evaporator sensors. These definitely cause issues. My HEVAC would randomly switch from cold to hot with temp set to 20deg. After cleaning the connectors it works much better.

Grrrrrr · Nov 27, 2017

pwood999 said:
Remember there's multiple temperature & other inputs to the HEVAC.
Road Speed - dunno why the HEVAC needs this ??

Cooling effect on the condenser of the air passing?

pwood999 · Nov 27, 2017

Grrrrrr said:
Cooling effect on the condenser of the air passing?

Shouldn't matter. The flap position to achieve the desired air temp should depend on the relative temperatures of heater core & evaporator.

Hevac Havoc

gencybay

gatvol

brianp38dse

Well-Known Member

gencybay

gatvol

brianp38dse

Well-Known Member

biketeacherdave

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

The Mad Hat Man

Well-Known Member

gencybay

gatvol

dubbleRR

Well-Known Member

martyuk

Well-Known Member

Mukiwa

Well-Known Member

martyuk

Well-Known Member

pwood999

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

pwood999

Well-Known Member

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