no heat

[pensfan74]

My 2000 blazer has no heat. When I turn on the heater/defrost it only blows cold air. Could this be the thermostat? I wanted to flush my radiator fluid also, what is the proper way to do this and where are the drain plugs located. I should use dex-cool right. What is the proper way to mix 50'50 dump half out of jug and fill half up with water in the jug? If not the thermostat what else could be the problem/ What is proper way to replace thermostat and where is it located exactly?? Thanks, starting to get cold here in PA...

[Rick Norwood]

Originally Posted by pensfan74

My 2000 blazer has no heat. When I turn on the heater/defrost it only blows cold air. Could this be the thermostat? I wanted to flush my radiator fluid also, what is the proper way to do this and where are the drain plugs located. I should use dex-cool right. What is the proper way to mix 50'50 dump half out of jug and fill half up with water in the jug? If not the thermostat what else could be the problem/ What is proper way to replace thermostat and where is it located exactly?? Thanks, starting to get cold here in PA...

This thread may help you. I no longer recommend Dex-Cool.

http://www.automotiveforums.com/vbul...d.php?t=729213

[MT-2500]

On flushing the best flush is to remove a heater hose and let the engine running pump out old coolant with engine running and a water hose in the rad cap.
Flush until water is clear.
Then get a good can of engine flush and add and run as per instructions on can.
Then flush the flush out of it.
At that time back flush heater core to and make sure coolant is flowing threw HEATER CORE BOTH WAYS.

On draining engine and rad I just let the engine pump most of it out the heater hose when flow quits I remove lower rad hose on lower part and drain .

Then replace the stat and when adding coolant add up to 2 gallon of pure mix stuff.
Pure mix is cheaper and if you use 50/50 there will always be some water left in system causing the 50/50 mix to be less than 50/50 when done.
Bleed air air out at heater hose and you should have heat.
If not you may have other problems.

But beware of draining old coolant and flush down your drains.
Some places it is illegal to drain it down you sewer system drains.


As to the type of coolant.
Later model GM cars and truck all come from factory with Dexcool
You have a choice of old green or Dexcool or Prestone has a new type extended life coolant yellow in color that is a good replacement coolant.
What ever way you go always service coolant ever 3 years or 50K and you will have few problems.
Good Luck MT

[pensfan74]

I just remove the lower rad hose and not the drain plugs on the rad or the engine block?? Its ok to just flush it out from the lower rad hose? Where is the heater core located at? Should I replace my thermostat too? When I put in new rad fluid should I use 2 gal straight and 1 gal water? What is engine flush in a can and where do I get it? Thanks...

[MT-2500]

Flush out from the heater hose.
Remove lower rad hose for draining.
Add straight coolant after draining.
Try to get close to 2 gallon in it and the finshish fill with water.
Parts places have flush in a can.
The heater core is on the end of heater hoses going threw firewall.

[fuzzbutt]

FWIW, I've done this several times in the past 4 years to solve my nearly no stop cooling system issues. Follow MT's advice. It works well.

As far as no heat. Besides the obvious, low coolant level, your core could be plugged solid. Warm up your engine to 180+. Put your hand on the larger of the 2 heater hoses. That in the one going into your heater core. Is it hot? Is it pressurized? Now how about the smaller hose? If they are soft or cold you have no flow thru the core.

Do this to gently get flow thru your core again. If you use too much pressure prepare for a big repair bill or learn how to remove some parts that the factory designed not to be removed too easily.

Buy a good length of the small diameter heater hose, I think it is 5/8" and the larger is 3/4". Get a female garden hose adapter from your local hardware store and a ball valve to regulate flow. Disconnect the larger hose at the intake manifold and drape it off your fender so you don't spray the gunk all over your engine. Unclamp the return hose and push on the new hose. Bring your garden hose over and connect it to the ballvalve. Slowly start running water thru the core. It is running backwards to the normal flow. I had to vary the pressure/flow the last time I did it to get all the chunks free. The heatercore acts like a filter and keeps all the crud blocking flow. This will work if it is not too bad. Try this if you still have no flow.

Stop running the water thru and instead disconnect the garden hose and stick your shop air on the end of that hose with a blow gun attached. Start blowing. Gently. I had to repete this a few times with my 2 year old core. I have not had any issues with it since I did this last back in February '08.

The rest of the motor like MT said and filler' back up with anything but dexcool.