Heat problems - no error codes

[bzbatl]

I have a strange problem that I haven't had time to let the dealer take a look at. I'm not getting any error codes in the dash LCD.

2001 Tahoe 5.3

I used to have the common issue of the heat getting stuck and having to let the truck sit for a while to get cold air again, but now I'm not getting any hot air... sort of.

When I first turn on the truck, it blows cold air for a good while (45 minutes in a 30 degree commute). Finally the heat kicked on for about 10 minutes, then went away again.

I noticed that my temp gauge spiked to about 240-250 when the cold air was blowing, and dropped right to the center at 230 when the hot air was blowing.

Is this an issue with the thermostat or that heater core thing under the kick panel?

 

[Rollin Thunder]

the over heating would mean a thermostat if i read what you described right, but and i remember from my classic car age is when a car over heats to turn on the heat, so it may cool off when the heat finally kickes in . but im still kinda confused, i would over heat because there is no coolent or not receiving coolent, but usually if the engine is over heated it should blow hot air through:skep: . was the compressor (snowflake) turned off??

230 is still a little hot though, normal is 200-210, as a rule of thumb, anything over boiling point is too hot

how did the truck run? i.e. had less power, didnt preform as well as it usually does, etc.

 

[bzbatl]

Running fine, no noticeable power decrease or engine issues. I have been getting ping from our crap 87 grade lately, so I've been filling with premium for the last couple of months.

I had it set to the defrost/floor setting, turned all the way to hot, varied between 2 and 5 on the fan setting cuz I was freezing my buns off. The A/C snowflake was off, and set to take in exterior air. Rear defrost was turned off.

Radio is working fine, all fuses are clear. All vents are working properly.

I'm saying 230, but I'm not 100% what's in the middle. It typically points directly 12:00 in the summer. Maybe it's a case that it has always been running too hot?

How much of a chore is it to replace the engine thermostat? $60 is a pretty pricey guess... but it's awash I suppose with a diagnostic cost.

 

[Rollin Thunder]

Running fine, no noticeable power decrease or engine issues. I have been getting ping from our crap 87 grade lately, so I've been filling with premium for the last couple of months.

I had it set to the defrost/floor setting, turned all the way to hot, varied between 2 and 5 on the fan setting cuz I was freezing my buns off. The A/C snowflake was off, and set to take in exterior air. Rear defrost was turned off.

Radio is working fine, all fuses are clear. All vents are working properly.

I'm saying 230, but I'm not 100% what's in the middle. It typically points directly 12:00 in the summer. Maybe it's a case that it has always been running too hot?

How much of a chore is it to replace the engine thermostat? $60 is a pretty pricey guess... but it's awash I suppose with a diagnostic cost.

210 is right in the middle on my 06, maybe that is what you meant.


dude i would take 60 any day of the week, is cost me 300 to replace the thermostat on our mercedes. just to get the heat to work!

 

[bzbatl]

Good call, it is 210. So I roll into NAPA to see if they have a thermostat, and dude says: "Are you sure your coolant is OK?"

So we go out and check, and sure enough, it's low. Fill up about half a gallon, and voila, the heat is working. $5 fix.

However, problem #1 is that the sensor isn't throwing an error code to me.

Problem #2 is, after driving about 30 miles, the heat went off again, and when I got home I checked, and my coolant is low again. I refilled it and will check for leaks in the morning when I have some light. I don't want coolant all over my garage floor

To top all this off, I had to stop at the tire store as well, because my alignment is off and it has been jacking my tire up. $165 for a 20" Goodyear Eagle GT.

Sigh!

 

[Rollin Thunder]

Good call, it is 210. So I roll into NAPA to see if they have a thermostat, and dude says: "Are you sure your coolant is OK?"

So we go out and check, and sure enough, it's low. Fill up about half a gallon, and voila, the heat is working. $5 fix.

However, problem #1 is that the sensor isn't throwing an error code to me.

Problem #2 is, after driving about 30 miles, the heat went off again, and when I got home I checked, and my coolant is low again. I refilled it and will check for leaks in the morning when I have some light. I don't want coolant all over my garage floor

To top all this off, I had to stop at the tire store as well, because my alignment is off and it has been jacking my tire up. $165 for a 20" Goodyear Eagle GT.

Sigh!

yup sounds like you have a leak, busted a tank maybe off roading, i did that once on my 99, it sucked. it also could be a loose pipe, does it only leak when running, or all the time?

i think the low coolent warning needs to be adjusted on these trucks, because i tested mine when flushing the coolent and it did not warn me until almost all of it was out.

 

[bzbatl]

Never been off road with it, I drive pretty conservatively, and I never see a puddle in my driveway or garage. I can only assume I'm losing it when it's running. I check my oil regularly (and did today, of course) - it's not leaking into the crankcase, thankfully.

Perhaps a hose running along the ground somewhere. I never smell it burning/cooking, like when I spill it when filling it, lol.

This is going to be a fun one in the cold weather. Anyone have any tips or tricks on finding coolant leaks?

 

[Rollin Thunder]

start it and rev it in N and have a buddy look, and have a scuba mask on.

the way we did it in the shop was to get a pump mine was manual looked like a mini tire pumper, but they have automatic now, that puts normal or extrime pressure on the system to see if and where the leak is.

http://www.sjdiscounttools.com/stn12270.html

 

[bzbatl]

Haha, I'll try the scuba mask method with my wife this weekend :lol:

Thanks RT. How difficult is it to change ALL the hoses in the Tahoe? Are there some that are a PITA?

Lord, I hope it's just a pinhole leak in a hose. Will be in a very bad mood if it's a metal part with a leak.