HVAC Warm at high speed and cold at slower speeds

[toomuch50]

Usually just a lurker on the site but my HVAC has been bothering me for months and I'm not sure what could be causing my issue.

For example if I have my heat set about 75 it is very warm when driving above 45-50mph but if I dip down to city speeds under 40 it is no longer warm and is blowing cool air. I generally have it at 72 when traveling at highway speeds and have to turn it up to 78 or so when in the city to feel the same warmth. Any ideas what I could look into? I have no idea where to start. Thank you for any help.

 

[CXS]

Have you checked your coolant level?

 

[YotaDriver]

Could it be a stuck thermostat? Does your temp gauge seem to be in the normal location when you're not taxing the engine much?

 

[asdfman7]

I've noticed this, too, in a way. I wouldn't say that I've felt cold air coming out of the vents, but on cold mornings I noticed that when I get off the freeway and slow down, there is a slight drop in the air temp in the cab. I just assumed that since i'm slowing down, there isn't as much air being forced through the air intake for the hvac system. And since your body has adjusted to the amount of air and heat coming out of the vents, you're sensitive to any minor changes in the temp. Just my hypothesis...:flame:

...And I just reread your post, seems like you are experiencing something a little different. Maybe try cleaning the inside air temp sensor in the driver side kick panel. Notice the little vent below the ignition? You'll have to pop the panel of to get to it but it's really easy to do... Two bolts down by the pedals and the rest is held on by retainers. Mine was a little dirty and I have noticed that the blower works a little differently now, or as it should...

 

[toomuch50]

Thank you for the quick responses!

Have you checked your coolant level?

Good question. Not for a while as it's on my list of items to flush and refill. I will take a look. On a side note I just installed a similar OME lift to yours but I am unsure how to tell if I have 884 or 885 coils up front. I bought the kit used and didn't see any marking.

Could it be a stuck thermostat? Does your temp gauge seem to be in the normal location when you're not taxing the engine much?

Temp gauge seems to stay the same position regardless of speed/taxing the engine. Stays somewhere right in the middle. Temp gauge was my first thought but I don't think it is since it seems to behave like it should.

...And I just reread your post, seems like you are experiencing something a little different. Maybe try cleaning the inside air temp sensor in the driver side kick panel. Notice the little vent below the ignition? You'll have to pop the panel of to get to it but it's really easy to do... Two bolts down by the pedals and the rest is held on by retainers. Mine was a little dirty and I have noticed that the blower works a little differently now, or as it should...

Ah maybe that will help. Hopefully I can try cleaning this tomorrow and see what the results are.

 

[CXS]

On a side note I just installed a similar OME lift to yours but I am unsure how to tell if I have 884 or 885 coils up front. I bought the kit used and didn't see any marking.

The only markings are a small white tape with the number on it. If that's gone I have no idea. Sorry.

 

[toomuch50]

The only markings are a small white tape with the number on it. If that's gone I have no idea. Sorry.

Yeah that's gone. Whichever they are I like them so far. Thank you though.