Probably a stupid question but with winter here and snow on the ground and a wrecked tacoma I need to figure out the heater in the 84 pickup.

It won't blow hot air. Do I just need a new heater core. The AC is disconnected would this have anything to do with it.

 

Double check that the valve on the firewall is actually working. Sometimes the cable can pop off. Check that. However, it's possible the heater core is shot.

 

my heater core was cloged for a # of years . I tried CLR to clean it , back flush .. tried everything .

my timing chain just broke the long side guide , so I decided it was time to do the heater core while I had the coolant drained for the timing chain job .

heater core is a huge job , I knew this and this is why I didnt do it before .
The complete dash has to be removed . It's a big job, but just wrapped up the re & re today .. had to order a couple of distributor o-rings , so Truck isnt running just yet , but should be tomorrow



.

 

It could also be the thermostat, stuck, wrong temp, or not one there. Also check the coolant level. When I clean my heater core (I do this every year at the end of summer), after draining it I fill it up with industrial strength toilet bowl cleaner, let it sit overnight, then flush it out several times with water. I've been doing this for 8 years, and no damage to my heater core yet. But I've seen some nasty crud come out after every flush/clean.

 

How much work is involved in flushing the heater core. I currently don't have a garage and work until its dark 6 nights a week. So most jobs I'm doing have to be completed in one day.

 

I can chime in on this one. To rule out some of the things old fart mentioned step 1. warm up the truck and turn the heater on full blast. step 2. feel the hoses next to the firewall. both should be hot just like the radiator hoses. If one is cold you got a clogged heater core. step 3. Let engine cool and drive down to your local DIY carwash real quick when nobody is around and pull off the hoses connecting to the firewall. Perform it hot at your own risk. Step 4. insert quarter into machine and shove the wand into the hose and blast the heck out of it. Do both sides. They treat the water at the carwash so don't worry about the runoff. If that doesn't work they used to make a 2 part radiator flush (acid and neutralizer). I think they quit making it because of toxic environmental reason.

This happened on my 86 and it worked like a champ. Nice 25 cent fix.

 

Ryan g. Are these the two tube you are talking about. The two right in the center of the engine bay coming out of the fire wall. The right one was getting hot but the left never did

 

by "left" i hope you mean passenger side. anyways yes those are the hoses. shove pressure washer wand in passenger side first the repeat on drivers side. watch for gunk to come out. Keep going until its clear water. x2 on checking that valve on the firewall for proper operation.

I know your going to ask "how" so when you pull off the drivers side hose take a peak inside the valve. see if its full of gunk. play with your heat/cool switch in the cab and watch the valve open and shut.

 

Thanks for the help guys. I used the car wash technique and it worked well. Put the wand into the passenger side one and just let it push the water out slowly with a couple bursts and then a little bit into the driver side. Heat isn't super hot but defiantly an improvement. Both hoses are hot now when heat is full blast. Great fix.

Ps when you take the passenger side hose off coolant will pour out. Be ready to plug it up. Caught me a bit off guard. Glad I had some water and coolant handy.