Diego Zuniga Posted December 20, 2016 Report Share Posted December 20, 2016 Hey guys this should be a easy one. My heater all seems to be there but how do I use it? I see there are a couple flaps under the dash that pull and push, then a knob on the dash with a fan logo on it and a knob on the heater itself. What do they do? Do these things blow hard? Mine blows but not to hard. It probably would not blow out a candle. 1 Quote Link to comment
banzai510(hainz) Posted December 20, 2016 Report Share Posted December 20, 2016 on hearter core knob it lets the water flow in the core. Fan is the fan. low med high Flap routes air up to defrost if you call it that 2 Quote Link to comment
wayno Posted December 20, 2016 Report Share Posted December 20, 2016 That is a common complaint about the 521, the defrosters don't work that great, and it takes forever to heat up the cab, it usually gets toasty in the cab around May. 3 Quote Link to comment
DanielC Posted December 21, 2016 Report Share Posted December 21, 2016 There are two parts of the heater system in the cab. The air box, and the heater box. there are five heater controls. 1. The knob with the four blade fan controls the heater fan motor, three speeds. 2. A lever below the dash, on the right, marked "shut" and "heat". 3. A tab on a door on the air box, behind the bracket on the bottom of the dash in this picture. 4. A lever below the dash, on the left, marked "room" and "DEF. 5. a lever on the heater itself, marked "off" and "heat". The fan knob, you already know. The lever marked "shut" and "heat" closes off or allows air to enter the heater box through the rubber boot. if this lever is in the shut position, no air goes into the heater box. Opening this lever allows air into the heater box. The tab on the door, on the air box allows air from the air box to enter the cab. If this door is open, toward you, air from the cowl will always enter the cab. It is independent of the air going to the heater box. If you shut this door, and shut the air from going into the heater box, you stop all air from entering the cab. You can also have both door open, some air directly into the cab, some air through the heater box. or all the air through one or the other. The lever marked "room" or "def" directs air after it has gone through the heater core to the cab, or into ducts that go up to the defrost ports in the top of the dashboard. If the lever marked "shut" and "heat" is in the shut position, no air enters the heater, no air comes out of the heater, no air can be sent to the room or def. A lever on the heater, marked "off" and "heat" allows engine coolant to either flow into the heater, or blocks it from flowing. It just stops coolant flow in the heater core. It does not bypass the core if it is in the off position. Heater operation, its winter, even in Sacramento. You want heat. Heater water valve on "heat" Lever marked "heat" or "shut" on "heat" Tab on air box door closed, away from you. Room and def lever directs where you want the heat to go. It helps the defrost work better if you open the wing windows partially, to pull air our of the cab, above the dashboard. You need to be driving the truck for this effect to happen. Heater operation next summer. Heater water valve in off position. Lever marked "heat" or "shut" on "shut" Tab on air box door pulled to you. Windows open. If your wing windows will stay, open them to scoop air into the cab In the winter, run a 190 thermostat. Get it from the Nissan dealer. Do not cheap out on a thermostat. Overheated Datsun engine warp the cylinder head. When was the last time the cooling system was flushed out? If the heater core is plugged, you will not get heat. When was the last time you cleaned out the heater box? it is easy for leaves, and other debris to get through the air box, and end up on top of the heater core, blocking air from going through it. Move the below dash levers to "heat" and "room", pull the fan knob out one click, and you should feel a pretty strong flow of air on the bottom of the heater core, just above the door on the bottom, of the heater. It is possible to take the rubber boot between the air box, and the heater box off, remove the heat water valve knob by removing the set screw, and then three clips hold the front of the heater on the heater box. You do not need to remove the whole heater, or drain the coolant water to do this. The ducts going up to the defrost vents can be leaking air or be damaged. They are 1 1/2 inches in diameter. I found some engine air cleaner preheat hose works for this. The defrost ducts under the dash are a brittle plastic, and held to the underside of the dashboard by one screw. This is one way I secured the defrost vents to the dash on one of my 521 trucks. 3 Quote Link to comment
Charlie69 Posted December 21, 2016 Report Share Posted December 21, 2016 That is a great Idea Daniel. Mind if I copy your Idea and modififying it by drilling holes in the plates and using my Harbor Freight stud gun for body work to spot weld thin all thread to the dash so they can be rmoved for disassembly and cleaning. Quote Link to comment
DanielC Posted December 21, 2016 Report Share Posted December 21, 2016 Charlie, you and anyone else can copy my ideas in this forum. 1 Quote Link to comment
Diego Zuniga Posted December 21, 2016 Author Report Share Posted December 21, 2016 Thanks for all the help and info. You guys are great! I will play with the heater and see what I get. So from what I am getting the blowing power is weak? 1 Quote Link to comment
wayno Posted December 21, 2016 Report Share Posted December 21, 2016 Thanks for all the help and info. You guys are great! I will play with the heater and see what I get. So from what I am getting the blowing power is weak? I carry a squeegee in my 521 work truck that I use on the inside of the windshield all the time. otherwise I would not be able to see till it warms up. All 521 fans are not weak, but my 71 Datsun 521 motor has gone out several times over the years, some blow good, not great but good, others are just plain pathetic, it depends on if you find a good one, and there are 3 or 4 different type of motors also, not all are interchangeable, I found the ones that are kind of a disc that the brushes ride on one side like a record player blow the most air if it is a good one, but they fry themselves more often than the ones that look like a regular motor, and they are way noisier also, never lost one that looks like a normal motor. 1 Quote Link to comment
DanielC Posted December 21, 2016 Report Share Posted December 21, 2016 Parking a 521 out of the rain helps with keeping the interior dry enough that the window does fog as much or often. Removing the cowl grill. and cleaning organic crud out of the chamber below the grill, will help also. There is a drain for that cavity in the center of it, it drains down the center of the firewall. Often the drain is plugged, and water is held there, and that causes the air drawn into the air box, and heater to be more moist. In the winter, putting a piece of cardboard in front of the radiator, and blocking off part of the radiator will let the truck warm up quicker, and run a little warmer. Cleaning the squirrel cage blower can remove any imbalance the dirt has caused. Be careful, the plastic can be easy to break. Removing the nut that holds the squirrel cage to the motor shaft, is risky, it is easy to break the blower fan. Removing the imbalance will let the motor spin faster, a clean blower will mover more air. You can remove the back plate off the pancake (flat) motor, and carefully clean the brush surface with mineral spirits. Mark the parts so they go together the same way, locating pins are 120 degrees apart, and it will go together three ways. Allow the mineral spirits to completely dry before reassembly. It is just held together by the the magnet of the motor. 1 Quote Link to comment
mklotz70 Posted December 21, 2016 Report Share Posted December 21, 2016 You can download the owner's manual here..... http://www.bluehandsinc.com/manuals.html and it will explain it too. :) 1 Quote Link to comment
Stoffregen Motorsports Posted December 21, 2016 Report Share Posted December 21, 2016 Heater blowers have become important to me lately. Some of my client's rigs need better defrosting so I have been thinking about this too. I wonder if having the motor rebuilt would help. I also wonder if you can bump up the voltage to the fan without too much worry. Maybe the original fan resistors could be swapped out with newer ones to help with low voltage issues. For sealing the ducting, I have been using a thin tan colored foam tape with an adhesive backing. It's been working out nicely so far. 1 Quote Link to comment
d.p Posted December 21, 2016 Report Share Posted December 21, 2016 I live on the east coast and I don't even use the blower. I just open the heater up in the cabin and it gets warm quick. I assume its just heat from the engine at that point? Or mine is turned on and I don't even know it (no knob). 1 Quote Link to comment
Lockleaf Posted December 21, 2016 Report Share Posted December 21, 2016 Heater blowers have become important to me lately. Some of my client's rigs need better defrosting so I have been thinking about this too. I wonder if having the motor rebuilt would help. I also wonder if you can bump up the voltage to the fan without too much worry. Maybe the original fan resistors could be swapped out with newer ones to help with low voltage issues. For sealing the ducting, I have been using a thin tan colored foam tape with an adhesive backing. It's been working out nicely so far. I've also been wondering this. In my head I was thinking of wiring a step up transformer in so that it could only function when the fan was already on high, then route power through the booster with a "turbo" button, or maybe mark the button "11" (cuz this one goes up to 11). Like this type idea, 12v to 18v step up. http://m.ebay.com/itm/291127754998 I figure it would shorten the fans life expectancy, but how unreasonably? 1 Quote Link to comment
Lockleaf Posted December 21, 2016 Report Share Posted December 21, 2016 Another option (if space can be found) would be to try installing 12v inline bilge type fans as pull fans. 1 Quote Link to comment
spdcrazy Posted February 24, 2017 Report Share Posted February 24, 2017 any updates on some of the ideas that's been thrown around here? I'm just starting my search, but I think I remember someone saying they used a Honda blower motor of some sort to get things moving? if I find more info, i'll attempt to link it here. 1 Quote Link to comment
iota Posted February 10, 2020 Report Share Posted February 10, 2020 I also wanted to bump this thread and see if anyone had a source for the knob on the heater unit (the "off-heat" water knob) - ours doesn't have one, and while I can find random plastic knobs online, I can't find the "lever" style that I've seen pictured in this thread. If anyone knows where to find something that is anything near to the original lever that would be great! (I have a 520 but our heater looks identical) 1 Quote Link to comment
Greaser2 Posted February 10, 2020 Report Share Posted February 10, 2020 I have a white knob but decided it would just break eventually plus the set screw was broke off in the valve shaft and I had to drill it out so went with this valve handle. Took the hole unit out, got the valve unstuck, cleaned and painted everything. The handle is from Hobby Lobby in the rustic drawer pull isle for $2.50. 1 Quote Link to comment
mainer311 Posted February 10, 2020 Report Share Posted February 10, 2020 Nice. Mine is half of a nutcracker. 1 Quote Link to comment
wayno Posted February 10, 2020 Report Share Posted February 10, 2020 They show up on ebay every so often, but they are aftermarket ones. 1 Quote Link to comment
Eomund Posted February 10, 2020 Report Share Posted February 10, 2020 I'm jealous of your guys systems. Mine leaked like a sieve so I pulled it from the system. I have a complete unit from a 280z that I'm looking into getting hooked up kinda. But I haven't got there yet. 1 Quote Link to comment
yenpit Posted February 10, 2020 Report Share Posted February 10, 2020 33 minutes ago, Eomund said: I'm jealous of your guys systems. Mine leaked like a sieve so I pulled it from the system. I have a complete unit from a 280z that I'm looking into getting hooked up kinda. But I haven't got there yet. You plan on retrofitting a 280Z heater assembly?? 😣 Ugh, you would be MUCH better off locating another 521 unit and/or heater core..........MUCH MUCH better off!! Since buying my truck a month ago & spending time on this 521 forum, I will start buying parts trucks! I've been buying & selling 510 & Z cars & parts for many years, just didn't pay enough attention to the truck series & the need for good parts! I know where one parts truck is in an old school junkyard that is closed down, so I am already working at buying that one, as I know the owner! TJ Quote Link to comment
Crashtd420 Posted February 11, 2020 Report Share Posted February 11, 2020 Just throwing this out there for the heater knob.... the post measured up as .236 which is 6mm.... Just so happens so are guitar knobs.... I'm poking around on Ebay and finding many different ones that would work.... Probably all would need a small mod to align the retention screw.... 1 Quote Link to comment
iota Posted February 11, 2020 Report Share Posted February 11, 2020 I actually noticed the same thing earlier today and ordered some knobs on Amazon, will report back soon 2 Quote Link to comment
Nippon521 Posted March 23, 2022 Report Share Posted March 23, 2022 I could use all things heater control.....someone ripped the knob off of the heater control box, I have a nubbin left, there's not enough even to JB weld it.....would love to find a heater core, would simply just love it...thanks for any assistance Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.