HELP!!!! Heater not blowing very hot!!!

1994 Metro, 3 cyl, 1.0 liter, 107,00 miles, automatic

Just last night my heater seems to have stopped blowing very hot. It's still warm, but not "hot" by any means! And it's starting to get cold outside! What do I need to check?

I have had intermitent problems with the thermostat... could this be related?

Thanks.

Dear Newbie, I think .. if your heater is not putting out .. easiest thing to check first is your coolant level. If your a little low, usually the first symptom is the heater core isn't getting the flow circulation to produce any measurable heat. Could be an ope thermostat too. But looking at the recovery tank and topping the coolant is the first & easiest step. Hope this helps. Otherwise get a wool blanket & move south! Thanks for taking good care of one of my Metros! (I love 'em) DangerDude

If it is cold outside and your thermostat is not closing, then the engine may
never get really hot.

The thermostat on my '93 Metro is quite easy to change.

As to the heater - I had two Jeep Cherokee's with the Straight Six engines
and both had the heater not doing very well.

I unhooked both heater hoses by the Firewall and hooked up my garden hose
on low flow and BACKFLUSHED the heater core.

You have to know which way the coolant is normally flowing to do that....

Anyway, I got a lot of crap out of the heater core - ground up rubber and one
rather large chunk of rubber!

After that, the heater toasted us when on!

DoctorBill

Did you install a new thermostat? If not, your old one could be bad and stuck in the "Open" position and not allowing the car to fully warm up.
Easiest way to tell is:

1. Start the car and run it (Or drive it) for about 10 min's with the heater on full HOT and blower motor on high.

2. Park the car, and while still running the engine.....Grab each of the heater hoses that are running into the firewall and see if they are Both Hot or just Warm?

3. If they are warm, but not Hot......Change the thermostat.

4. If 1 Hose is HOT, And the other barely warm or cold.......The heater core is flowing slow or is partially blocked with debris (Rust or Sealers).....Your going to need to flush the heater core out in both directions until the water is flowing CLEAR and Strong from it in order to get full heat. (Remove both of the heater core hoses from the engine and flush with a garden hose in both directions). In this case, I would not only flush the core in both directions...I would flush out the entire cooling system with Prestone system flush (Per Directions)...BEFORE you put "All New" Anti freeze in a 50% /50% mix with distilled water in your entire cooling system.

Do these tests and report back what you find out on the hoses (Warm Hot etc..).



I unhooked both heater hoses by the Firewall and hooked up my garden hose
on low flow and BACKFLUSHED the heater core.

You have to know which way the coolant is normally flowing to do that....

DoctorBill

Doc, the FULL pressure from a garden hose wont hurt the core, it helps to dislodge buildup.....Just dont put the nozzle on the end of the garden hose.......Hose only on full and flush in BOTH directions "Many, Many" times.....Wont hurt it either.....It's just a small radiator......Been doing this process for over 30 years now. If you really want to do the job right, flush out the entire cooling system several times (Thermostat removed and gooseneck put back on temp) ....1st time with a Good Prestone flush. If there's buildup in the heater core, Odd's are it's also in the rest of the cooling system too!

OK, sounds like stuff I can get to tomorrow - here's my questions...

* Which hoses are the heater hoses that run into the firewall?
* Where is (what is) the heater core?

OK, sounds like stuff I can get to tomorrow - here's my questions...

* Which hoses are the heater hoses that run into the firewall?
* Where is (what is) the heater core?

The Heater core itself is mounted Inside the car and Inside the Heater box BEHIND the dashboard. The 2 heater pipes that come from it just stick thru the firewall and attach to the 2 heater core hoses. The heater core hoses are the 2 Small heater Hoses at the Firewall....Open the hood, Stand on the DS (Driver Side) of the car and look down behind the engine. You'll see 1 Hose goes to the back of the Engine (Throttle Body Area) and the other hose goes into the Steel pipe that the larger heater hose from the radiator is hooked up too....Here 2 pics! With the engine COLD....Remove the heater hoses from the heater core itself or from the back of the TB and heater pipe (Still connected to the core pipes).......And flush away!....Your going too lose some Anti Freeze in this process....have some more on hand when you refill!

http://i25.photobucket.com/albums/c83/MrBBody/HeaterHoses1.jpg

http://i25.photobucket.com/albums/c83/MrBBody/HeaterHoses2.jpg

Geo Metro Heater Core - Approx 6" X 8" In size

http://i25.photobucket.com/albums/c83/MrBBody/GeoHeaterCore.jpg

The pictures were VERY helpful. Thanks,

I did everything - flush, replace thermostat, flush the heater core. There wasn't much "gunk" anywhere - not from the radiator, not from the heater core. However, the spindle (?) on the thermostat was bent. Don't know how that happened - previous owner maybe? Also there was NO gasket on the thermostat (there is now). We'll see how this impacts my heater and my engine temp. problems.

Thanks again

This is from a post at:

http://autos.groups.yahoo.com/group/thegeometroclub/

about this problem and solution:


Q and D [quick and dirty ] method for shock pulse core flush.

Take a piece of 1/2 pipe [PVC will do] and drill a hole in it to accept a
rubber tipped air compressor blow gun.
If you can "install" an air inlet with a valve that doesn't leak, you'll
stay drier....but this works OK.
Connect that to a water hose. An old 1/2" garden hose with a missing end
fitting is perfect...just jamb the pipe in there and secure it with a worm
[heater hose] clamp as needed. [Your degree of wetness will determine "as
needed" in a big hurry ]

Disconnect both heater core hoses from the engine.
Jamb your water feed assembly into one heater hose.
Jamb another length of 1/2" pipe into the other hose going to a pan of
some sort to catch the crap..so you'll know when none is any longer being
flushed out...and so it doesn't go "everywhere". [meaning, mostly all over
you ]

Turn on the water full force.
As the water is flowing through the core [er..seeping through the core? ]
place the air feed nozzle into the hole in the pipe and give it short blast
of air..sending a shock wave though the core to break up and dislodge the
crap. Shock Shock Shock Shock many times.

Do that till you no longer see any crap in the catch pan.

Then switch heater hoses and go at it from the other direction.
Go back and forth a few times.

When you have a full flow and no crap, you're done.

I "think" the hose coming out of the intake manifold is the back flush
direction and should probably be done that way first.

To shock the radiator:
Reconnect the hose that goes to the tube on the tranny, take the radiator
cap off and repeat the shock treatment to dislodge crap in the radiator.
[water should flow from bottom to top ]
Or....clamp a length of the garden hose on the tube nipple, bypassing the
now clean heater core.

Then
Remove lower heater hose and drain plug and wash the rad from the top
down to clear out settled debis.

DO NOT "pressurize" the components with 120 PSI air unless you like split
seams.

Don't be surprised if you have to do this several times over a few
months, as the buildup of crud in the cooling system is "systemic" and the
heater core has the smallest passages and clogs more easily.

ode

The pictures were VERY helpful. Thanks,

I did everything - flush, replace thermostat, flush the heater core. There wasn't much "gunk" anywhere - not from the radiator, not from the heater core. However, the spindle (?) on the thermostat was bent. Don't know how that happened - previous owner maybe? Also there was NO gasket on the thermostat (there is now). We'll see how this impacts my heater and my engine temp. problems.

Thanks again
Yes, But now that you have:

1. Flushed the core clean
2. Flushed the cooling system
3. Installed a new Thermostat
4. Put in new anti freeze in the entire cooling system

The heat should be nice and hot!........Post back what you find out from the fixes?

It was easy enough to do without all the "fancy" instructions from the other post. The garden hose seemed fine all on its own.

Anyway, the heater is nice and toasty now and the previous problems I was having with the engine temp gauge not working properly are a thing of the past too.

Thanks to everyone for your help...:grinyes: