Author Topic: Defroster help:  (Read 4774 times)

Offline Stewart G Griffin

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Defroster help:
« on: September 29, 2016, 08:11:48 pm »
i know----besides carrying a roll of paper towels are there other quick tips to help out the defroster?  It's just not cutting it.   

i know by 80 or so GM cars had very good defrosting systems because i remember going shopping for new cars with my parents to the pontiac and olds dealers and i was very impressed at the speed and efficiency of the defrosters.

Offline Irish_Alley

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Re: Defroster help:
« Reply #1 on: September 29, 2016, 09:05:53 pm »
working a/c? modern cars the a/c kicks on whenever you have on the defrosters (at least gm)
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Stewart G Griffin

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Re: Defroster help:
« Reply #2 on: September 30, 2016, 07:18:31 am »
working a/c? modern cars the a/c kicks on whenever you have on the defrosters (at least gm)

Ah, that must be it.  i took mine out.   i'll just stick with the towels for now.......

Offline ehjorten

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Re: Defroster help:
« Reply #3 on: September 30, 2016, 08:30:26 am »
Are you sure your heater box is up to snuff?  I have rebuilt 3 of these now and this is what I can tell you from my experience.  The main problem with defrost in these trucks is the foam on the end of the defrost door!  It gets old and brittle and falls away!

I have used pliers and bent open the staples that hold the foam on, removed the remnants of the old foam, used some wide foam like that used to seal canopies to the bedsides (about 1-1/4" wide, 3/16" thick with a PSA backing...going off of memory here, but just that roll of pickup and camper tape that is wide enough to cover the defrost door) and put the staples back in and bent them back over.

Make sure your blend and mode doors are functioning properly, put new foam tape around the perimeter of the heater core opening and couple all of that with a new blower motor...maybe even a new heater core while you have the thing apart and you will be amazed how well it works!
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline Stewart G Griffin

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Re: Defroster help:
« Reply #4 on: September 30, 2016, 08:15:02 pm »
Are you sure your heater box is up to snuff?  I have rebuilt 3 of these now and this is what I can tell you from my experience.  The main problem with defrost in these trucks is the foam on the end of the defrost door!  It gets old and brittle and falls away!

I have used pliers and bent open the staples that hold the foam on, removed the remnants of the old foam, used some wide foam like that used to seal canopies to the bedsides (about 1-1/4" wide, 3/16" thick with a PSA backing...going off of memory here, but just that roll of pickup and camper tape that is wide enough to cover the defrost door) and put the staples back in and bent them back over.

Make sure your blend and mode doors are functioning properly, put new foam tape around the perimeter of the heater core opening and couple all of that with a new blower motor...maybe even a new heater core while you have the thing apart and you will be amazed how well it works!

Will look into it.  Thank you.

Offline ehjorten

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Re: Defroster help:
« Reply #5 on: October 11, 2016, 07:32:01 am »
You also want to make sure all of your vacuum pots are working properly and don't have a ruptured diaphragm.  I just push actuator on the diaphragm and then cover the vacuum port with my finger.  It should hold in that position if the diaphragm is still good.  Alternatively if you have one of those Silverline vacuum pumps you can use that to see that the diaphragms moves and holds a vacuum.  Lastly...check all of your vacuum hoses to make sure they are in good repair.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6