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110 V8 - no air from any dash vents but blower motor is working


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Hello - Spent alot of time searching for the answer to this one, but no luck. I have a restored 1988 110 V8 (imported it to the States). I have fixed quite a few small niggles on it, but this one has me stumped. I get no heater air (warm or cool) from any of the dash vents. I have checked the cables etc, and the blower motor certainly sounds like it is cranking out some air. The lower dash flaps do move (removed footwell vents to check this). I can stick my fingers up there and I feel no air movement whatsoever. It seems as if I have two unappetizing choices here to investigate this further - pull out the blower and heater core, or remove the entire dash?! I started pulling screws out of the dash but then got put off when I seemed to be making no progress in getting anything to move. Seems like top down is the way to do the dash from my research. But before I spend the time and gray hairs to do that - Does anyone have any idea why I might be getting no air and/or how to diagnose this?

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I've worked on this recently after bulkhead swap, there are two flaps operated by the cables, the cable that operates the lever on the side (as oppose the top) of the heater box moves a metal flap/door that blocks up the hole into the dash (the lower part of the dash is actually a tube through which the air passes). Maybe your flap is wedged shut or cable snapped. I'm sure the link posted will answer all your questions though.

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Thanks very much. Believe it or not I had found that thread but after reading part way through I foolishly didn't think it applied. But Guy009's clue above helps a great deal - I heard that flap between the heater box and lower dash thump shut when I was adjusting cables - but didn't know what it was. I think mine may be operating backwards somehow. When my fan speed lever is full down on 2 (high fan speed), I think that flap shuts which sounds like the exact opposite of what it should do. But it would explain why I have never felt as much as a whiff of wind from any of the vents since I have owned it. I was getting some of the cable housing pulling through the clamp for that side lever as well, so I will need to figure out what is going on with the flap. Step one, put screws back in dash!

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Check the motor is wired the right way round it could be sucking instead of blowing or full of mud easy to check by removing the cowl from under the wing then you can see the fan blades through the opening.

Mike

Thanks Mike - Not full of mud, but could be wired backwards - I can feel a little breeze leaking around the heater box output to the lower dash, so I think it is trying to blow. I am betting my flap is shut...

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Flap is fine - checked that and cables and flap working as they should. Then thought Mike may be right and fan was spinning backwards, but no it is correct. So I am left to think air can't get through heater matrix (which is strange since it is likely new as the rest of the components on the heater box are). Everything very clean but who knows maybe something is in there. I did feel quite a bit of air leaking out around top of heater box (riveted-on section) so sealed that seam with silicone - not dry yet but doubt it makes that much difference. So unless I am still missing something, looks like I will need to pull the box out when I get a chance and have a look at the matrix element?

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WOW - PROBLEM FOUND! Removed heater box (left coolant hoses and wiring attached). Found a jagged hole in what must be the back side of lower dash, and a sort-of tear-drop shaped hole in firewall. Now this vehicle was probably converted to LHD from a RHD, so not sure how much of this is artifacts from that. Looks like someone had drilled a big hole in the dash lower backside, then cut grooves and tried to bend the metal tabs in to expand the hole! I have no idea what this SHOULD all look like... but I assume not this. There was also a foam sheet that appeared to be blocking the heater box exit perfectly. So it may work now - the blower does blow pretty well - even with the jagged hole, but wondering if I should try to enlarge that hole. The metal (back side of dash) looks quite thick however. Need to figure out how to post pics...

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This is not a land rover bulkhead but the hole for the heater is the same.

IMAG0993.jpg

The square hole should line up with the heater out let. The tear drop you describe would of been the hole for the steering column on latter bulkheads this hole is square to make it easier to change from right to left hand drive.

IMAG0966.jpg

Mike

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Thanks again Mike. Yup that is the hole in the firewall that the blower is trying to force air thru. Looks to me if I want to get it right I will need to remove lower dash, cut a proper rectangular hole in it and also the firewall. No idea why the rectangular piece of foam was in there blocking air flow. I get flow now out of the dash vents but it is pretty weak - not surprising considering the small jagged hole in the back of the dash.

defenderheaterbox1

defender heaterbox2

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Think i'd be looking at the bulkhead more closely, if they have bodged the heater into a RHD steering slot, have they secured the steering brackets correctly?, looks like the footwell panels have had repair/plates over them.

The hole for the heater should be square/rectangular, and there should be a piece of sealing gasket you can buy to seal properly.

Have the rest of the bits been swapped over properly, i.e lower dash heater box/wipers. The brake pipes look to have been replumbed

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Conversion/refurb was done by Liveridge which I though had a good rep - although they do see to be defunct now. Rest of vehicle seems to be quite well done as I had it inspected by a local expert. But I will be looking at details more closely - but there does seem to have been good attention to detail in many spots.We had it in a very corrosive beach environment all Summer and the paint and underside coating held up great. Hoping this may be an isolated example of one worker taking a shortcut. We have had the vehicle for over a year with only minor issues. In fact more things work properly on it than our 97 NAS 90 (which we have owned since new).

The heater box does have the gasket along the firewall. Fan intake does not line up well with wing intake so will try to remedy that. The lower dash flappers work fine.

Steering brackets? I will have a look and/or post photos. Yes the footwell holes for rhd pedals do have plates riveted over them.

Trying to figure best approach to enlarge heater box hole. Probably not doable from the engine compartment - which could save removing the dash. At least I have some air now.

Thanks again for all the comments.

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Thanks again Mike. Yup that is the hole in the firewall that the blower is trying to force air thru. Looks to me if I want to get it right I will need to remove lower dash, cut a proper rectangular hole in it and also the firewall. No idea why the rectangular piece of foam was in there blocking air flow. I get flow now out of the dash vents but it is pretty weak - not surprising considering the small jagged hole in the back of the dash.

That rectangular piece of foam is normally glued to the flap in the heater box so that the flap seals when you close it to prevent dust entering. Looks like the glue has gone and it then fell/flopped over the (too small) bulkhead hole.

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That rectangular piece of foam is normally glued to the flap in the heater box so that the flap seals when you close it to prevent dust entering. Looks like the glue has gone and it then fell/flopped over the (too small) bulkhead hole.

This is my thinking too Simon - the flap lining having got stuck to the wrong face.

There's also the heavier section rectangular foam 'gasket' that fits between the heater box and bulkhead. If that's missing you can lose a lot of air into the engine bay.

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Thanks Simon and Petrol. That explains the mystery foam! May never have been glued on - everything in there looks new and no signs of glue residue. I do have the rectangular foam gasket that seals against the firewall. So once my hole is enlarged I should be all set. It is better already that I at least have SOME air flow. Not looking forward to attempting the hole enlargement!

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Mike thanks that would certainly be the preferred way so that holes line up and I don't need to pull the dash! I will talk to some of my friends who have more metal-working experience. Probably would need to actually remove the heater box this time (remove coolant hoses) for clearance. If I pinch the hoses off before removing from heater box, what is the secret to get rid of air bubbles in coolant once re-attached? I saw somewhere that folks run the motor with radiator cap off?

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Yes you will need to take the heater out completely. Air shouldn't be a problem if the hoses are on the right way round ie fill the matrix from the bottom. But failing that I just connect it all up but leave the hose clips loose run the engine up bleed the air from both pipes one at a time then tighten the clips.

Mike

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  • 3 weeks later...

FIXED - I now have plenty of air into the cabin and a working defroster and heater. I cut through the firewall and the lower dash in situ from the engine compartment. I was able to leave coolant hoses attached to the heaterbox - I just tied it up on top of the radiator expansion tank while I cut. I used a combination of a drill (to get some initial corner holes) a Dremel EZ456 cutoff wheel (5 of them) and a sawzall with metal cutting blades. It wasn't that hard to cut through both pieces of metal once I got some initial openings. Each tool came in handy in various spots depending on the access angle. I also discovered a thin bulkhead which is normally the end of the air channel in the lower dash on a rhd vehicle. This was about 3/4 of the way to right of my desired rectangle, so I used metal snips to cut most of it out. I then painted the bare edges, and put silicone seal in the gaps between the firewall and dash. All in all it worked very well even if my new hole is not exactly perfectly rectangular! I also stuffed some insulation inside the dash to the left of the hole (basically just dead space) as all the vents are to the right of the hole when looking from the front. I used some silicone glue to attach a plastic bulkhead fashioned from pvc sheet inside the dash just to the left of the hole to keep the insulation from creeping over. Thanks again to all those who helped out on this thread. Next: get the rear wiper and defroster working!

The new hole I cut in firewall and lower dash for the ventilation fan

Defender Heater box strapped out of the way so I could cut through firewall

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