I know it is a bit early for this converstaion, but I am working on getting my weak defrosting solved before soggy fall arrives here in the Pacific Northwest. I have taken a crack at this today, but am now stuck. If anyone has ideas for me I will appreciate it!

The situation is this:
With the engine running and warm and the heater lever on (up) I get heat and defrost on both sides of the cabin But, it is more powerful and hotter on the passenger side. When I turn on the in-dash fresh air blower and set everything to defrost (all levers to the right), it actually overpowers the heat on the drivers side and that air is cool/warm. The pass. side is still fairly hot, however, and that side stays nice and clear in the winter.

So today I am troubleshooting:
-Adjusted flapper box cables to make sure they can open all the way - made no difference.
-With engine OFF and heat lever on, there is not flow at all coming out of the downstream side of flapper boxes. Heater blower is running.
-With engine RUNNING, flow and temp are the same whether the blower is running or not (with heat lever off I manually opened them to test )
-The heater blower has only one duct and it is connected to driver's side only. But that is wierd, since driver's side is weaker. So, I pulled that duct to test flow of heater blower - it blows but a bit weak. Should this thing be stonger? It sure makes a lot of noise for what it puts out.

Now I am stuck:
-Am I missing something about this system should work?
-Is my driver's side heat exchanger clogged?
-Or is my blower motor too anemic to do any good?

Attached are some pics in case any of you can spot an oddity.
Click to view attachment
Click to view attachment
Click to view attachment

That is a bit strange. Maybe take the hose off the down tube in the engine bay and make sure you have volume there. I would suspect somthing wrong with the impeller more than clogged HEs. Nothing should get down there to clog it.

I had the same thing, the pass side defrosted faster than the drivers

I had a splitter on the blower that pumped air into both HE's.

914's heat and defrost systems are less that adequet at best. There is plenty of heat put off by the HE's, the prob. is getting it to the cab. The blower motor puts out alot of air but it has to pump it a long way. There have been a few different fixes like boat bilge blowers in line but the longevity was in question.

The best fix I have seen is to add another blower motor so there is one for each HE. This is what I am doing to mine

If memory seves, I think the articale was on the pelican parts site

Keith

Bilge blowers are damn noisy. Wouldn't really recommend them.

I think the heating system is very good when in proper operating condition. Leaky HE's let air blow out, thus reducing volume entering the cabin. Bad sealing of components allow air to leak out and smelly oil fumes in. I believe people would rather dump money into paint and engine than getting their cabin heating/cooling up to snuff.

Lube the mechanicals for the lever system up front, make sure everything moves freely. Remember, you're likely dealing with 30+ years of neglect...

note the flapper valve to body hose is disconnected in the first picture. i'm pretty sure that's the driver's side. for max defrost/heat the 2 upper levers on the dash controls need to be fully to the left and the lower one fully to the right. moving the upper levers to the right mixes the hot air with fresh outside air. the lower lever directs the air to the defrost vents or the underdash outlets. the fresh air box fan pushes non-heated air. the engine compartment fan pushes heated air. to see how well the engine compartment fan works, set the dash controls for max defrost. with the engine off, key in the on position, pull the lever (red knob) on the tunnel to the fully raised position. you should hear the engine compartment fan activate and feel air coming out of the drivers side (after you attach the above mentioned hose) dash vent (with the engine cold and NOT running) and the air will be cool. warm up the engine, raise the floor lever, and the air should be hot enough to warp vinyl records. while driving with controls set for max defrost, the hot air should BLAST out of the defrost vent. still less than hot air? examine the paper wrapped hose that runs from the drivers long in the cabin to the valves under the front cowl. the bottom of that hose connects behind the speaker.

k

Some questions are loaded but this one is nuclear

I'm thinking of using an electric heater/blower deal from car quest and/or route a small oil cooler in the cockpit with a little wee fan. As mentioned above noisy and heavy is the stock setup.

I installed the bilge blower fans to pull the hot air into the cabin. They mount over the flange behind the speakers in-line with the hose. Noice is not a problem if they are attached to a three speed switch and run on Med spd. I've used there for three years now.

Here's a pic of the parts:

Freekin awsome idea there bro. Iza be shopin!


Boater's World:

#35-679-0865 is 3" in and out 240 CFM for $22.99

#35-679-0436 water resistant at 3" in and out 135CFM for $27.99

cassidy, in pict # 2 the white object near the he should be a metal j-tube. is it the same white hose that's attached to the engine fan or is the j-tube just painted white?

k

Additionally, there are two "valves" built into the engine impeller housing which are generally missing. These are at the bottom of the impeller housing, covered by the "S" shaped warm air ducting .... just little aluminum plates that close when the heater blower is activated .... otherwise the feeling is that the heater blower would over power the engine impeller flow (backflow into the impeller housing).

Thanks Slits! I just noticed them last weekend and wondered what they were for.

Are these visable from under the car ?

yes. but you have to remove the 2 S shaped ducting pieces to view them.

k

Thanks for the input folks. I am trying to get this thing up to spec rather than add new things to the system. I have done a lot of archive research. The issue is that, for whatever reason, the blower motor is not doing it's job of adding flow at idle and low rpms.

The hose is disconnected from the flapper box in the pic becuase I was checking flow there to begin my diagnosis. Sorry if that confused things. The J tube looks white in the pic - it is white-ish rust-ish in real life.

Right now, with the key on, engine off, heat lever pulled up and blower making noise, I get NO flow at all coming out of the flapper boxes and some flow coming out of the blower (when I pull the hose to check it). The HE's are definately leaky at the flapper boxes - but not that bad. Where is this blast of air of which Kevin speaks?

The rest of the system is well screwed together and functional (hoses, dash levers, etc.. At this point it sounds like I need to dig deeper into the plumbing at the HE's, J tube, "valves" in impeller etc....I am afraid that I need to replace the old leaky HE's. That is $ I don't have right now!

I do understand that the fresh air blower is a separate system. I am forced to use it because I have a low speed urban commute with many lights and my revs don't get very high. The flow in the cabin at idle is minimal. I get plenty warm, mind you, just not enough flow for good defrosting.

Further dis-assembly will have to wait until next weekend at this point - other obligations today.......but have any tips for taking this stuff apart?

Thanks.

i don't have an aux heat fan on my car. the blast of hot air is what should be streaming out of the defrost @ 3k rpm. how leaky are your hes? you didn't mention that.

The heat flow is proportional to the engine speed. At idle and low rpms, the flow on my 914 has always been meager.

Second, if everything else is checking out, have you experimented with opening the drivers side window to create a draw? While not at idle, I have to open the window.

I ran the fan again this morning and crawled under the car for a quick peek and there is air flowing in weird places down there, I am thinking it might just be leaking out of the HE's.......it's just weird that I get absolutley nothing heading into the car unless the engine is running. I mean not a whisper. I hadn't suspected the HE's since I have not smelled exhaust fumes in the car. Guess that was wrong.

Yes, I usually do crack the window and that helps. I get plenty of flow at 3000 RPM and the defrost works fine.

Well that has me scratching my head. If your problem was the result of leaky HE you would think it was the same regardless of the sourc of the air. The air from the cooling fan and the aux fan merge together before the heat exchanger.

Did you have a chance to look for the check valves that Slits described?

Did you have a chance to look for the check valves that Slits described?
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Not yet, but that sounds like a smart first step...I will get in there and poke around a bit....



thanks.

Sounds like the flappers that SLITS mentioned are missing. Yes, you can lose a good amount of air from leaky HEs but remember, the leaks are from the surrounding tin separating from the exhaust piping so, naturally, you won't get exhaust fumes. Now, if your engine is leaking oil onto the HEs and it drips inside you'll get fumes until you clean/burn off the oil (BTDT ).

I'm not sure if this will work but with the engine OFF, turn on your heater fan (ignition switch in the ON position), reach into the fan housing where the engine cooling air intake is and see if you can feel any air. This would definitely indicate missing flaps at the bottom of the fan housing.

Haynes shop manual, page 22, item #33. There's one on each side.

Brilliant

Just in case I'll add the standard caveate. If you have the key on and the motor not running for any length of time it is good practice to disconnect the 12v connection to you coil to protect your points.

Ah, good point swl. If done briefly, though, it will be okay.

In fact I just did this test on my POS (deet-dee-dee!). I'm getting a small amount of air blowing out Even easier method, especially if you have big hands that can't reach into the fan intake or short arms and a big gut in the way, is to remove the timing plug on top of the engine and hold a piece of tissue paper on the hole. If it blows upward then you know those little flaps ain't working too well or not at all.

I already know my flaps are in so-so condition so I expected this. They act as one-way air flow directors so air will travel out of the fan housing but won't flow in, like when the blower turns on.

Now if you'll excuse me, F1 is back on the Speed Channel

SLITS and Toby nailed it.

I have no flaps, no retaining pins, zilch. I went ahead and removed the warm air guides to take a peek. It is a relief to know what the issue is. Now, anyone know if I can buy them? I will start looking into the usual suspects.....

Thanks!

You should only need the blower is for situations where you've got to keep the engine RPM's low.

The thing that helps heat output is RPM's. Your heat should run you out of the car if you keep the engine wound up. Once the engine gets up to operating temp, keep the RPM's at 3500 and above and you should have plenty of heat.

Having the warm air components in proper working order is definately the place to start. If you keep the engine wound up though, the aux blower and the little anti reversion flappers don't come into play.

The bilge blower looks like a decent idea, but I would prefer to push air through the system vrs pulling it. I have seen a thread on Pelican about adding a second stock blower, so you have one on each side.

914-6's do not have any auxillary blowers, and you get plenty of heat from the stock heater boxes.