PhredzK512
1/2 ton status
My '87 K5 takes forever to defrost & doesn't throw out the heat like it should. Is it in the heater core or do I need to find a new blower motor to put in? Any suggestions would be helpful... 
CK5
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Needing Defrost Power...
- Thread starter PhredzK512
- Start date
kdo1958
Registered Member
There is a guy on youtube who show how to back clush the heater core.
It might need a new thermostat,and a 195 degree one is what belongs in it...it may have a cooler one or none at all in it,or one that never fully closes and lets the engine reach full operating temperature ..
It could be a blocked up heater core,while you have the cooling system drained out,you can back flush it with a garden hose..they do clog up after awhile,and if any radiator sealer was used,it usually ends up blocking the heater core up..
Also make sure the defroster duct hoses are intact,and its actually moving the air up to the ducts at the windsheild--if you have A/C sometimes a vacuum motor fails to switch from "heat" to "defrost"...if you have manual controls with no A/C,make sure the blend door that switches from cold to hot air is working--you should be able to see that by pulling the glove box down and looking in there...
It's not impossible some mice or other critters moved in and nested in the blower motor housing or the heater core box too...if the fan doesn't seem to be blowing much air,it might pay to remove the blower motor and see if any nests are in there..
It could be a blocked up heater core,while you have the cooling system drained out,you can back flush it with a garden hose..they do clog up after awhile,and if any radiator sealer was used,it usually ends up blocking the heater core up..
Also make sure the defroster duct hoses are intact,and its actually moving the air up to the ducts at the windsheild--if you have A/C sometimes a vacuum motor fails to switch from "heat" to "defrost"...if you have manual controls with no A/C,make sure the blend door that switches from cold to hot air is working--you should be able to see that by pulling the glove box down and looking in there...
It's not impossible some mice or other critters moved in and nested in the blower motor housing or the heater core box too...if the fan doesn't seem to be blowing much air,it might pay to remove the blower motor and see if any nests are in there..
double check that all your ducting is properly connected under the dash.
These old crappy heat/defrost ducts like to come apart. Mine works great after i sealed all the leaks, fixed the blend doors, etc.
When functional, these systems do their job.
These old crappy heat/defrost ducts like to come apart. Mine works great after i sealed all the leaks, fixed the blend doors, etc.
When functional, these systems do their job.
