Hi, new here. I'm not sure if this thread belongs here so if not I apologize in advance.

I'm trying to diagnose a problem with my mom's IS250, shes been complaining that it takes forever for the heat to actually heat the interior of the car. I also noticed that the temp gauge sits at C for a very long time.

So I decided to take her car for a drive tonight with an OBD2 scan tool that I use in my own car to watch the ECTs. I found that after it hits about 115-120 degrees it takes FOREVER for it to reach 150 and at that point the heat is just starting to come out of the vents. The temp creeped up to 160 very slowly and stopped there, went back down to 155, then shot up to 178 degrees. When it finally got to 178 degrees (after 20 mins of driving) the heat was finally working. The temp gauge was pointing about 1/3 of the way to the left.

Does this car take a long time to warm up, or is there something wrong here?

Now I'm not familiar with this engine, but I dont think what I saw was normal, plus most cars stay closer to 190 degrees and dont jump around. So I figured I'd ask before she takes it to the dealership and they say "This is normal, please leave". Because to be honest with you our Lexus dealer sucks in the customer service dept. Nevertheless, it sucks when its 20 degrees outside and you have to wait 15-20 minutes for the heat to start working.

Could this be a bad thermostat or something wrong with the climate control system. Has anyone else had this problem? Any info would be appreciated.

Thanks.

 

def. sounds like the thermostat.....its sticking open

 

Something definitely sounds wrong. Should heat up w/in 5 mins.

 

I'm with Scottina08 -- sounds like a classic case of a radiator thermostat stuck open. Fixing it will not only get her heat back, it should also improve her gas mileage.

 

For me, the system seems to cool and heat OK.

problem i have is that in the winter i always get too much heat in my face. seems like there is always too much air blowing to the face vents even when set to floor.

also seems like passeger temperature is lower than driver fat same setting.

to get face air cool ebough so i am not uncomfortable my feet (especially the left) are freezing

 

I've never encountered any of these problems with my AWD...but now that you bring it up, I'll pay more attention. But I highly doubt it would be a concern for me...as long as it heats and it cools properly.

 

I've noticed both on mine and other comments in the forum that the IS250 takes forever to warm up and the same with the white exhaust "steam". I'm guessing that with the large amount of oil combined with the engine efficiancy, not much heat is generated. Plus you need to have the dealer shut off the "foot-air leak" in the c-best settings. Otherwise the car "leaks" cold air on your feet no matter what the climate control is set to.

 

The cars do take a long time to warm up because:

1) Large capacity sump for such a small engine
2) Engine coolant is routed to the transmission which is also cold
3) Aluminum block

To warm up the engine more efficiently, she should drive for a while with the heat off, and she should have the air set to recirculate mode to prevent drafts of cold air from entering the car. Once it warms up some she can turn on the heat, but leave the air on recirculate so you have a cumulative effect of heating already warmed air -- rather than constantly bringing cold outside air up to temp. This reduces the heat transfer from the heater core and that will help the engine come up to temp faster.

None of this means there isn't a problem with the thermostat...

 

I would check the coolant level just to be sure but overall yes its true than IS and other Lexuses take forever to heat up when its really cold outside. -20 C is the case. We have harsh winters here and most IS owners noticed that the car warms up (and heater too) much longer than they experienced with their previous volvos, mercedes and stuff