Hi all, new to group.
Have a 90 Blazer full size, throttle body 350. Has been slow to develop
decent heater output for a long time. I have put in a new radiator
(needed anyway) and thermostat with no appreciable improvement. The
temperature guage in the cab quit working at some point too, could be a
Also the brake light has been flashing a code 19 for quite some time,
has decent brakes though, Id just like to know what is up with that?
Have you checked to see how well the heater core is flowing? Could be
Get some heater hose at a parts store and then get a female water-hose
connection from Wal-Mart, or any hardware store. Put the connection on
the heater hose and connect that to the heater core with the other hose
disconnected from the radiator. Take your "new" heater hose and
connect it to a garden hose, and then hit it with the water on full to
flush the core out. If you get very little water coming back out the
other heater hose, you may need to have the core properly cleaned or
maybe even replaced.
I wouldn't think the temp gauge would be tied into the heater problem
at all. The sending unit for the gauge should be in the driver's-side
head, under the exhaust manifold... IIRC, it's right between cylinders
1 and 3, although it could be 3 and 5 (can't remember). Make sure the
connection is good and that the wire hasn't been burned off by exhaust
heat. The sending unit is cheap, so you may as well replace it anyway.
Someone will hopefully post a decent method of testing the actual
gauge. You could just apply voltage to see if it pegs, but I wouldn't
try it until you knew how much it would take without damaging the
Not sure on the brake light. My K5 is an '86, so it doesn't have any
new-fangled computer thingy on there ;-)
Thanks for the reply Jon,
I had been thinking it could be the heater core, I just didnt want to
go there, now with your
post I see it may be a necessity. Just didnt wanna! Still dont!
Them new fangled computer thingies are a pain in the rear end! Pun
Jon R. Pickens wrote:
Maybe you'll get lucky and blow a bunch of debris out with the
I didn't ever try to change one out. In the C/K trucks it looks pretty
accessible, but that doesn't mean it'd be easy. If you do have to
remove and/or change it out, let me know how tough it is. I'd just
like to know in case I ever need to do it.
Soon as I get some free time to mess with it, Ill try flushing first.
Called the Zone, 26 bucks for the new core. Much cheaper than I thought
it would be.
If/when it happens, Ill let ya know! Looks like a lot of interior stuff
has to come out.
The heater ducting, glovebox, and kicker panel, and the computer.
Remind me to disconnect the battery first!
Jon R. Pickens wrote:
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