Strange Heater Behavior

[Pilchard]

This is an odd one...........

My radio died so I got a used one off eBay. I had my local garage fit it today. They had the car in for a thermostat change to see if it would shorten engine warm-up time on these cold mornings.

Anyway................. the eBay radio works fine but................. it seems I'm now only getting hot air on the passenger side of the interior & pretty tepid air blowing out on the drivers side. Tried all the settings........ screen, floor, dashboard vents.......... all the same; hot on left & tepid on right.

I can't work out why.......

The only thing I can think of is this.............. Because the heater control unit is fixed to the radio, & so has to be disconnected & re-connected to enable the radio to be swapped, one of the two heater control connector blocks is now not making a good connection &, because for some reason the heater controls COULD BE ZONED LEFT & RIGHT (are they?), the message isn't getting through to the drivers side & it's just blowing tepid on that side.

The Air Con is just a basic one...... not Climate Control. But if it was a Climate Control system (if Toyota's systems zone the interior left & right like Audi's etc), that might explain how I'm getting this effect.

Any ideas anyone ?

[alan333]

I'd start by making sure the coolant hasn't got an airlock somewhere.

[Exvec]

Worst case scenario ..the servo motor on the heater control is playing up...best case scenario there's an air lock somewhere in the system in which case..rev the engine at around 3000 rpm until the cooling fans operate,have a go at squeezing the hoses (top),keep removing the header tank cap and replacing this should eventually expel any air lock if this is the case ..let us know how you get on :D

[mcorban]

Was the Battery disconnected while they changed the radio.

The reason i ask is you may need to reset your aircon control panel by disconnecting the power.

Leave it disconnected for about five minutes and power everything up again after.

The servos may need to home.

[Pilchard]

Thanks for all the suggestions chaps. Am taking the car back in again today so I'll print out your replies & give them to the mechanic. I'm sure he'll take no offence at being offered help.

If the 4 mile drive at 50mph don't get the temp gauge up, then I'll know the stat (genuine Toyota part) change was a waste of time & money. My glass IS half full though............ we can now get Radio 4 again

I'm not challenging the air-lock suggestions but........... if it were an air-lock, then ALL of the air being blown into the interior would be either cold or just tepid. It could be possible that the heater matrix itself is partially air-locked with the bottom of it running hot & the top cold........ but to give the symptoms I'm experiencing........hot on left & tepid on right.......... it would have to mean that there is some kind of Zoning at the heater matrix & air destined for the left of the interior gets blown through the bottom of the matrix & air for the right through the top. That sounds nuts.

Testing the electrical connection - servos - power - turn-it-off-again............... all sounds a more likely one, but strangely........with the left & right anomaly......... would still suggest there is some kind of ZONING built into the design. Maybe to save money, Toyota had the more lowly models share certain aspects with the top of the range models,.... even with Lexus.

As I don't know though, I'm ruling nothing out.