The last couple of mornings the temperature has been around 15 degrees.I have been letting the car warm up for at least 30 mins. and the air is warm and the temp gauge is at 1/4.I figure it would be around the half way mark and I would have hot air coming from the vents.Is this normal for this kind of weather or is my thermostat hung open? Going down the road the air turns from warm to not so warm when air is hitting the radiator.

 

Heater core is restricted. Gotta pull the lines and wash out the heater core. Mine was so plugged, I had to (carefully) use compressed air.

 

Didn't think of that.Is it because the antifreeze builds up when the heat isn't used in the summer?

 

Nope if you look at one of the lines going to the core, it has a restrictor in it. That doesn't help in washing out the sludge that builds up over time. Inside the engine, build up on the water jacket walls sloughs off and clogs everything.

I believe the core has smaller passages as well. It is a widely known problem with 4th gens.
None of my other vehicles I have or ever had have had this problem.

 

So I just need to take it out and flush it out and watch all the crap come out? How hard is it to remove?

 

Just let the car idle for 40 mins. without the heat on and the hoses were hot as was the radiator cap and the hose to the thermostat.The heat was hot also.Think I'm going to replace the thermostat first since it will be the easiest.It's not as cold now and it still takes to long to get to operating temperature.

 

You don't need to "take it out". Pull the hoses off the water pump and flush through the heater core with a garden hose, working in both directions. Make sure you don't get the Opti wet.

But if your coolant temp gauge is accurate, and it wasn't getting above the 1/4 mark for an extened period after a cold start, I wouldn't attribute it to a clogged heater core. You are probably on the right track with the t'stat. What temp t'stat do you have now? I've noticed it takes a couple minutes extra to warm up on a really cold day, with the 160* t'stat.

 

Maybe you should run a 180 tstat in the winter and run a 160 in the summer? May help the car warm up and get you warm faster?

 

The difference to me was only about 2 or 3 minutes to nice warm air, when the temp dipped down into the 10-20*F range.

 

I just replaced my 160 thermostat with a 180. The 160 simply doesn't heat up the vent air enough in the winter, warm isn't ok. 5 minute fix.

 

It's a 180*. Gonna try to replace it today.Should I nose it up after I install it to remove the air pockets or will any air even get into it?

 

http://shbox.com/1/4th_gen_tech2.html#thermostat_change

 

Thanks.