Heater not working..

I have a 97 s10 blazer. About 2 years ago, before winter i had a problem with pressure, along with actual heat coming out of my system. i put in a new heater core, as big of a pain-in-the-ass as it was, and everything was fine through the last two winters. I had a radiotor problem last week, had a new radiator installed, and since returning from the shop, have no heat. Pretty good pressure, but no heat. I took off the heater hoses and ran water through them to see if something was clogged, but still no heat. Could it be something else with the heater core? Or possibly something simple like the thermostat. Much appreciated.

where is your temp gauge running?

where is your temp gauge running?

My temp gauge is running about normal between 150-180. I even let the car heat up for a while with still no heat. Since i flushed the two heater hoses, i've not driven it a long distance. I will turn it on tonight when i get to work to see if it is working. Until then, any other suggestions/ideas?

There may be air still trapped in the heater core. Burp it and see what happens.

Their is a heater valve for these units in the bottom of the case this is a damper it has a vacuum operator.
Their should be a dial in the dash which turns from heat to def or ac. They sell them at the dealer. You can use a vacuum gage to determine if you have vacuum. Check the vacuum at the engine I have found this fitting plugged and had to remove and clean it. Normally it has a few branches for a few lines.
With the temperature you stated I don't understand how your engine is operating effeciently because it is like operating with the choke on.
I had a customer who was getting about 3mph because he was operating about 150 deg. A new 195 thermostat jumped his gas mileage back to I assume around 12-15 mph.

I have a 97 s10 blazer. About 2 years ago, before winter i had a problem with pressure, along with actual heat coming out of my system. i put in a new heater core, as big of a pain-in-the-ass as it was, and everything was fine through the last two winters. I had a radiotor problem last week, had a new radiator installed, and since returning from the shop, have no heat. Pretty good pressure, but no heat. I took off the heater hoses and ran water through them to see if something was clogged, but still no heat. Could it be something else with the heater core? Or possibly something simple like the thermostat. Much appreciated.
Could your door not be opening and closing? Stuck on the cold side.

Sounds like the themostat to me. I have a bad one as well. I say that because I belive you should be running 180 to 195. not sure but 150 to 180 sounds a little low unless you have that temp. themostat in there. Gently touch your upper radiator hose after you have driven for a while. If it's cool then you know you have a problem. (I am not sure if that is an actually good diagnosis but I have heard people say to do it)

150-180 is pretty cold.

Sounds like the themostat to me. I have a bad one as well. I say that because I belive you should be running 180 to 195. not sure but 150 to 180 sounds a little low unless you have that temp. themostat in there. Gently touch your upper radiator hose after you have driven for a while. If it's cool then you know you have a problem. (I am not sure if that is an actually good diagnosis but I have heard people say to do it)

hmm thanks for all the suggestions guys. yeah, it does seem to run a bit cold. but also i thought, because i had the heat cranked and the two heater hoses going into the heater core werent really getting warm, that there was somethin clogged. but im not sure.

When you change the thermostat vent out the system or jack up the front end. After it is running at operating temp.shut it down and refill when cold.
Lack of anti freeze will also cause a cold car. They only other time I saw a car use this much fuel was caused a crack in the exhaust manifold by the O2 sensor. Just like smoking 3 packs a day.
The computer doesn't start working properly until around 190 degrees.
The S-10 I was talking about was a throttle body and the customer could notice it pouring gas into the car. I had a otc4000e tester and watched the temp when driving. If you have plenty of gas money you are still causing pollution.

It sounds like you're running no thermostat. I'd do what the others are suggesting and run a 185-195 degree one. Also, check the valve in the heater hose to make sure there's vacuum at the line when the A/C is set to heat and the engine is warmed up. There's a chance the valve might be closed and not allowing water to circulate through the heater core.

It sounds like you're running no thermostat. I'd do what the others are suggesting and run a 185-195 degree one. Also, check the valve in the heater hose to make sure there's vacuum at the line when the A/C is set to heat and the engine is warmed up. There's a chance the valve might be closed and not allowing water to circulate through the heater core.
I replaced the thermostat with a 195 degree one. There still is no heat however. I don't necessarily think it is a vacuum problem but just the fact that it is clogged up. There was so much sludge and nasty gunk up in the hose where the thermostat was and even some in the rad cap that it is possibly causing a clog up somehwere in the hoses or heater core? I guess i'm down to one last option i think, which is a complete flush. Also, i heard Prestone makes a good system flush that might clean that out of there. Any more suggestions?

I replaced the thermostat with a 195 degree one. There still is no heat however. I don't necessarily think it is a vacuum problem but just the fact that it is clogged up. There was so much sludge and nasty gunk up in the hose where the thermostat was and even some in the rad cap that it is possibly causing a clog up somehwere in the hoses or heater core? I guess i'm down to one last option i think, which is a complete flush. Also, i heard Prestone makes a good system flush that might clean that out of there. Any more suggestions?
The good flush came in a can with two parts. One for a flush one for a neutralizer when done . I would try and find a old parts store with some of this cleaner. Any new product is EPA rated and doesn't work as good. First I would remove the thermostat and put a tee in the heater hose open the drain and flush with a garden hose on a gravel drive after you drain the anti freeze. It is poison don't have your dog around. Don't overpressure the system. Also flush your heater lines. Garages are regulated and use a power flush system and disposal. Probably around $60 to $80 for this job.

The good flush came in a can with two parts. One for a flush one for a neutralizer when done . I would try and find a old parts store with some of this cleaner. Any new product is EPA rated and doesn't work as good. First I would remove the thermostat and put a tee in the heater hose open the drain and flush with a garden hose on a gravel drive after you drain the anti freeze. It is poison don't have your dog around. Don't overpressure the system. Also flush your heater lines. Garages are regulated and use a power flush system and disposal. Probably around $60 to $80 for this job.

alllright. i went to a radiator shop about 5 miles from here and the guy said he can blast 140lbs of pressure through there and knock anything out. He also said that chemical flushes arent the best cuz he ran into a blazer before with a head gasket problem that the chemical ate it away. He's charging me $45 so that might do the trick...

Just watch he doesn't damage your heater core with that high pressure.

A lot of shops charge $60 to $80 for a power flush. Hopefully he's stretching the pressure he uses. If its a reputable shop he will fix it if it damages your cooling system.

hmm.. okay. well, what's the maximum pressure to use without definately damaging something?

It depends on what he is doing. As an example he disconnects both radiator hoses. He has a pressure on his air compressor he probably has a fitting to hook to the air hose. He might set it at 16psi hooks up the hose to the heater hose he gets ait through it. He then disconnects it and puts a water hose on it. Say he uses 60psi shop water pressure. He will crack the valve and as the mud is flushed he will open the valve all the way. As the other end is open he is flushing with 60psi until the water runs clear but their isn't 60 psi pressure on the system. I have removed the thermostat and disconnected both radiator hoses put a hose in the top hose a foot or so and ran the water until it was clear.
Radiators I usually have a shop clean and rod them. They take the top off and have a flat rod they push through or they will sell you a new one if to bad.
If he runs a shop I'm sure he knows he is doing but I'm not sure you understand what he is doing. You would hear he blows up radiators.
My pressure tester on a closed system you check what the cap is rated at and don't try to exceed it. Say a 16psi cap over 20psi you can ruin an old radiator.

Before having the whole thing pressure flushed, check the temp of the input and output hoses to the heater core at the firewall. Although 150-180 may be a little low, it should be plenty to feel heat in the cabin. I suspect it may be the HVAC Heater blend door actuator, which unfortunately, is located on top of the heater core box. It's electrically driven and not vacuum actuated. I found it while changing my heater core and replacing a vacuum actuated door to the defrost outlet. You can see a good photo at rockauto.com under heat & a/c.
You may still need a flush. I had the same gunk after about six years. Cost me a radiator, heater core and auto part store flush. I think it's the Dex-cool. I changed to the green stuff.
I hope that it's not the heat-a/c blend door motor. A real pain to get to is all I'll say about it.
It could just be an electrical issue. I don't know about the fuse(s) that feed it.
good luck

Problem solved. Thanks for all the help guys. I had a radiator shop do a quick flush of the heater core. Everythings back to normal.

I don't think your problem will be solved for long.

You better go get your coolant changed seeing it is now started to mess up. Flushing the heater core will only be temporary.

The worn out coolant will return and clog it again.

I don't think your problem will be solved for long.

You better go get your coolant changed seeing it is now started to mess up. Flushing the heater core will only be temporary.

The worn out coolant will return and clog it again.

Hmm. well i mentioned prior i had a new radiator installed about a month ago, and a flush and re-fill was done that. Won't that be enough?

Hmm. well i mentioned prior i had a new radiator installed about a month ago, and a flush and re-fill was done that. Won't that be enough?

Yes, sorry about missing that.

Better safe and say something than assume. ;)