Rd 400h Heater temp changes

[Ricktc]

First time on this form. We have a 2008 RX 400H and the heater blows hot when I accelerate and switches to cold when slowing or sitting at idle. Is temp controlled by vacume? If so I think I have a vacume leak. Any ideas how to trace for a vacume leak. Everything else seems to work fine. Thx Rick

[TrevC]

Hi Rick...welcome to the Forum

It does sound like a vacuum leak if the temperature is controlled by vacuum.

Usually, vacuum leaks can be traced by running a combustible gas (in very small quantity...e.g. small gas torch on low setting or Brake Cleaner) around the suspected areas with the engine running at idle and if the speed increases slightly then it is drawing in the gas and combusting it, then you know where the leak is.

Another method is to use a Smoke Generator which does just what it says and you introduce the smoke into the vacuum lines with the engine off and see where it comes out...simple, but not cheap to purchase.

Let us know how you get on with it.

Cheers  Trevor