Truck Overheats & Heater doesn't heat up & AC doesn't get very cold

**porterusaf** · 04-30-2009, 06:24 PM

First quickly, I'm not a mechanical idiot, I had a 2005 GTO that I did alot of engine mods and mostly by myself... And it's nice to have a truck now, but I'm having a few issues.

Alright guys, so I'm basiclly having three problems...

Firstly my truck doesn't totally overheat (to the point of steam/engine problems) but the thermostat in the truck gets up to around 250 degrees and a warning comes on the dash that engine temperature is high... It only does this for short periods of time, usually at slow speeds, then goes away... (I'm guessing radiator or thermostat)

Secondly my heater heats up very slowly, and takes a while to get up to temperature (guessing thermo).

Thirdly my AC doesn't get very cold, it works, but not well...

So what do you guys think? It's a 2004 Silverado Z71 w/ 55000 miles. If I just get my thermo replaced should that fix the problem or am I looking at something bigger? Any recommendations on tests to do or how to go about figuring this problem out?

Thanks y'all.

-Porter

**Jimmiee** · 04-30-2009, 07:53 PM

I would check for air in the cooling system first. Also make sure the fan is working correctly as the fan makes the coolant and A/C both cooler by pulling air through the radiator and condenser.

**porterusaf** · 05-01-2009, 12:13 AM

Thanks I'll check that out...

**Evan** · 05-02-2009, 01:12 AM

Its 5 yrs old might as well go and spend 8 bucks and get a 195 thermostat.

**vncj96** · 05-03-2009, 12:59 AM

I would also do a power flush of the entire system, maybe something is plugged

**dwill3015** · 05-03-2009, 03:02 PM

Plugged heater core perhaps? My son has the same probs on his Ranger and his core is plugged.

**grimreapersshadow** · 05-03-2009, 06:22 PM

you might also see if your fan clutch is working properly if you turn the fan by hand when the motors off and theres no resistance then its needing replacement if its really bad then you can hold the fan still when the motors running dont try this if your not shure it will cut yours hands up pretty bad

**Springthing** · 05-03-2009, 09:21 PM

I'm going to go for clogged/plugged heater core as well.

**porterusaf** · 05-04-2009, 02:00 AM

See the thing is that makes me a little lost is that when it overheats, it corrects itself rather quickly. I could be driving at 45 mph, the temp will go really high for about 30-60 seconds, then drop back down to where it should be or maybe a little high on the gauge. If you guys think a flush will help, I'll get it done. Don't have the equipment anywhere close to me to do it myself sadly... I'm also going to get my thermo replaced just in case.

**Springthing** · 05-04-2009, 11:22 AM

Clogged core doesn't take much - just a garden hose, really. Look for the two hoses on the fire wall and (with them NOT hot, of course!) take them off and almost gently shoot some water from the hose through them. If you get junk coming out then you're doing good. If water hardly passes then you might have to think about a new heater core - it might be too tightly packed with junk.

I've a link somewhere I'll PM you if I find. It might be helpful for you.