BEEBANI Posted March 21, 2008 Report Share Posted March 21, 2008 I have a question about my 620 heater, probably been asked before.....I have cold air coming from the "flapper" on the bottom of the heater box when I'm going down the road. Full blown heat coming from the defrost vents, but cold air down below. This is with both levers on the control all the way over to the right. Do I have something not working right, or am I using the heater wrong? Quote Link to comment
Bleach Posted March 21, 2008 Report Share Posted March 21, 2008 check the action on the wire that closes that flapper. Then see about putting a thin strip of foam to seal that door closed. Quote Link to comment
datzenmike Posted March 21, 2008 Report Share Posted March 21, 2008 Make sure that the big black knob on the heater itself is pulled out fully or cold air will blow out above the consul. The bottom lever adjusts the amount of hot water flowing through the heater core. The lever above it, when in the left OFF position and as far over to the right as the half way DEFROST position, holds the bottom (floor) flapper closed and that forces the heated air up the defrost tubes to the wind shield. When the upper lever is moved from the DEFROST position, the flapper door begins to open until fully open at the far right HEAT position. If you have heated defrost air you have to have heated air coming out of the flap door. Check if this door is opening. When open you should be able to look inside and see the heater core. Quote Link to comment
BEEBANI Posted March 21, 2008 Author Report Share Posted March 21, 2008 with both levers over at the right, the flap door on the bottom is all the way open. The black round knob is closed. Quote Link to comment
moparvwfreak Posted March 21, 2008 Report Share Posted March 21, 2008 are you sure the flap is even there??? mine is missing completely. Quote Link to comment
BEEBANI Posted March 21, 2008 Author Report Share Posted March 21, 2008 are you sure the flap is even there??? mine is missing completely. O.k., seriously....I was kidding when I said newb question! Have you seen my truck? Do you really think I wouldn't have made sure the flap was there? Yes, it's there, I said that in both my posts, it opens and closes when I move the bottom control knob from cold to hot. Quote Link to comment
Llittle_Llama Posted March 21, 2008 Report Share Posted March 21, 2008 damnit, i gotta pull my dash soon so i can see what all you fools are talking about, lol Quote Link to comment
BEEBANI Posted March 21, 2008 Author Report Share Posted March 21, 2008 damnit, i gotta pull my dash soon so i can see what all you fools are talking about, lol all I gotta say is......wow.:confused: Quote Link to comment
datzenmike Posted March 21, 2008 Report Share Posted March 21, 2008 Holly shit!!!:lol::lol: Quote Link to comment
datzenmike Posted March 21, 2008 Report Share Posted March 21, 2008 With the door open, sorry flapper,:D you should be able to see the core. The fan blows air down through it and out the flapper and or if it's closed up, through the hoses to the wind shield. Can't see how you could have hot on one and not on the other.???????? Weird. Get dwnshfter to pull his dash and look. Quote Link to comment
BEEBANI Posted March 21, 2008 Author Report Share Posted March 21, 2008 Get dwnshfter to pull his dash and look. Exactly......and he wants to do a ka swap.:lol: Quote Link to comment
BEEBANI Posted March 21, 2008 Author Report Share Posted March 21, 2008 With the door open, sorry flapper,:D you should be able to see the core. The fan blows air down through it and out the flapper and or if it's closed up, through the hoses to the wind shield. Can't see how you could have hot on one and not on the other.???????? Weird. It seems like it gets worse when I'm at highway speeds too, like the air is straight in from the firewall or something. Quote Link to comment
Bleach Posted March 21, 2008 Report Share Posted March 21, 2008 Dwnshfter should just do a 240SX dash and heater swap at the same time as the engine swap. That would be the simple way to do things. Quote Link to comment
]2eDeYe Posted March 21, 2008 Report Share Posted March 21, 2008 I was gonna post something witty, but I think dwnshfter cover it lol.... Quote Link to comment
datzenmike Posted March 21, 2008 Report Share Posted March 21, 2008 The front of the heater, including the pull knob is held to the main body by nine spring clip... things. Ping them off with a screwdriver and remove the front cover and you should be able to see the squirrel cage, Hey dwnshfter! the heater fan is squirel powered! :D just fuckin' with ya. Just below the squirrel cage, the core is mounted horizontally and has foam rubber around the sides to prevent cold air from going around it. The core will pull out toward you if heater hoses are long enough. Wouldn't hurt to remove all the hair, leaves and mouse turds on the core anyways. To replace the spring clip things, place in position and press hard in the center and they 'snap' into place. Quote Link to comment
moparvwfreak Posted March 21, 2008 Report Share Posted March 21, 2008 all i was doing was covering all the bases. thats all. hell i didn't even know mine was missing until i looked and tried hooking up a cable. sometimes its the simplest things that make ya pull your hair out. Quote Link to comment
datsunaholic Posted March 21, 2008 Report Share Posted March 21, 2008 That's funny... the door on the bottom shouldn't move when you move the Cold-HOT lever. The bottom door only moves when you move the Off - Defrost - Heat lever. 620s don't use a blend door like modern heaters- the door's sole purpose is to open and close the floor vents. The Cold - Hot lever ONLY controls the coolant valve on the side of the heater box. Of course, there's another flapper- it's up on top, of course, with the big pushknob. Pushed in opens the vent wide open (cowl air straight through) and pulled out, the air is directed through the heater core. Mike, I only recall 4 clips. Are you sure you aren't quoting your 720 heater setup? Quote Link to comment
BEEBANI Posted March 21, 2008 Author Report Share Posted March 21, 2008 It is 4 clips Doug, I just put a new front cover on (thanks Bleach) and I cleaned all the shit out down there while I was at it. I'll check the levers again, but I believe it was the lower slide lever that was moving the flapper. Quote Link to comment
datzenmike Posted March 22, 2008 Report Share Posted March 22, 2008 The bottom lever adjusts the amount of hot water flowing through the heater core. The lever above it, when in the left OFF position and as far over to the right as the half way DEFROST position, holds the bottom (floor) flapper closed and that forces the heated air up the defrost tubes to the wind shield. When the upper lever is moved from the DEFROST position, the flapper door begins to open until fully open at the far right HEAT position. :o Yup... four. I looked away from the '78 FSM to type and looked back at the fan removal paragraph. Nine to disassemble the whole housing. Three screws, two clips for the 720. The case splits vertically left and right. Core is as big as a 620 rad! Quote Link to comment
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