No heat when cold

[Tman]

I have an 88 ranger, and we’re going through our first cold snap (got down to -1 last night) of the year currently, so of course my heat has stopped working. In more mild conditions the heat works fine, but the colder it gets outside the Less heat I get in the cab. I’m thinking I will need a new heater core, but in the mean time I’ve found my “outside air” controls are now stuck to the fresh air setting, bringing in the frigid temps to the cabin! The diverted flap that switches weather the air is coming through the fresh air intake or the recirc is blocked by a build up of pine needles and other dirt, and the fresh air intake is under the cowl. I can’t seem to find any good access points to clean this area out, has anyone successfully cleaned out this intake area? Any thoughts and suggestions are welcome!

 

[rusty ol ranger]

Theres grey plates on the firewall to access wiper linkages. If you remove those you might be able to shove a shop vac hose up in there.

Are you aure thats whats going on? You dont have a stuck thermostat or something?

 

[RobbieD]

Pulling the blower motor will also give you more direct access, to clean the trash out of the HVAC intake plenum.

>>> Make sure that there's no leaves, pine needles or other flammibles close to the blower resistor block next to the blower, as this can cause a fire.

Welcome to TRS!

 

[Tman]

Theres grey plates on the firewall to access wiper linkages. If you remove those you might be able to shove a shop vac hose up in there.

Are you aure thats whats going on? You dont have a stuck thermostat or something?

Thanks for the info, I gave that a try today. Wasn’t able to find a vacuum with a small enough hose that still have enough power to suck out those pine needles (they’re really in there good) but it is a good access point. Going to keep trying.

the thermostat seems to be functioning properly, coolant gets to operating temp fine and stays there, and the hoses going into and out of the heater core are warm. There does appear to be some build up on the walls of the radiator, which has me considering taking it in somewhere to get a flush done to see if it helps. I drained the radiator last week when installing a block heater and it came out pretty clean.

 

[Tman]

Pulling the blower motor will also give you more direct access, to clean the trash out of the HVAC intake plenum.

>>> Make sure that there's no leaves, pine needles or other flammibles close to the blower resistor block next to the blower, as this can cause a fire.

Welcome to TRS!

I started pulling the blower, but the access point through the firewall has a wire mesh over it, and there wasn’t an obvious (to me) way to remove the mesh, any advice dealing with that? Did I overlook something? It would be the perfect access point but I’m hesitant to cut out that mesh.

 

[RobbieD]

I don't recall a wire mesh blocking access. If you can post a picture of what you're seeing it may help jog the old memory.

On my '84 (which should be the same as your '88) '90 and '94 trucks I've pulled a bunch of debris out of the air box on the engine side of the firewall through the blower hole. And more importantly you can get to the blower resistor block area (the block itself is easily removable). If you get dry leaves debris around that resistor block it can cause a fire.

Here's a manual view of an '88 non-AC (going by your HVAC control head) firewall, both drawings blower motor on the left:

Wasn’t able to find a vacuum with a small enough hose that still have enough power to suck out those pine needles (they’re really in there good) but it is a good access point. Going to keep trying.

If the debris is old and really packed in, if you have access to an air compressor you can try using a blow gun to break up and move the packed in stuff. A blow gun that can take a hard tube extension works good.

Another handy tool you can use for debris removal is a flexible grabber tool like this:

to get in places that you can see but not get your hand. You can one of these just about anywhere; parts stoes, Home Depot, eBay, Amazon.

And it's pretty easy on the older trucks to pull the cover off the heater core, to check for crap around it.