car question
 

last night while driving home from lowes (which involves a pretty good drive up a hill: elevation difference ~1800 ft), i noticed that my engine temp was getting on the high side. It wasn't out of the band, but it was up on the edge.
This morning, I checked the radiator and it was full. However, the one odd thing I have noticed is that within the last 2 weeks or so, the heater sometimes just blows cold air. So when I need heat, I turn it on, then off, what a few minutes and try again for warm. Usually in 5 mins or so I get warm air.
Are the sensors/etc involved in both processes connected? Any ideas?

have you tried calling Car Talk?

is that the click and clack radio show?

yes it is. if you tell them about your leno appearance, I think you are more likely to get on the air.

thermostat? clog?
 

How old is the car and when is the last time you had your radiator flushed? Could be that your thermostat is not working (so the coolant water is circulating just within the engine) or there is a clog in your system due to deposit of scale/gunk/whatever. I once had a car where the engine temp was plenty warm but the heater didn't heat well, turned out the lines had a bunch of gunk accumulated which was resolved by flushing the system -- I went so far as to remove a number of the hoses and clean them separately.

Brian, can you upload that Leno appearance on Youtube? I missed it the first time and would like to see it.

It's a 99 Nissan Frontier truck. 80K miles. I've never had the radiator flushed.

I bet this solves it. We had a cold air blowing heater (in a Nissan in fact) and it was the thermostat.

I once had Jetta that would vapor lock and the hot engine light and buzzer would come on. Drove it across the nation that way. It only vapor locked once, outside of Grand Junction. Eventually, a new fuel pump solved the vapor locking, but the hot engine light and buzzer continued to come on. Beating the dashboard was the only solution I found. I was born in Idaho.

Sounds like your thermostat is sticking to me. I'd start there.

is that generally easy to fix?
I'm trying to teach myself how to do basic repair.

i sure wish i would have taken auto mechanics in HS. it would have saved me more money in life than that karate class.