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| no heat https://slantsix.org/forum/viewtopic.php?t=31155 |
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| Author: | 1974duster [ Tue Sep 16, 2008 7:53 pm ] |
| Post subject: | no heat |
hey guys it was been a while since i have post there my duster has been running great the one problem that i have is i have no heat i think the fan that push the heat broke how do i change something like out |
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| Author: | slantsixbob [ Tue Sep 16, 2008 8:39 pm ] |
| Post subject: | |
well what do you mean by no heat? do you turn the fan switch to heat and get cold air or do you switch it on and no air at all? let me know and ill try to help as much as possible. |
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| Author: | 1974duster [ Tue Sep 16, 2008 9:08 pm ] |
| Post subject: | |
there heat but the fan is not push any of the air when it is on |
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| Author: | slantsixbob [ Tue Sep 16, 2008 9:51 pm ] |
| Post subject: | |
has it worked before? if so id check the blower motor, that could have gone out. also check your air ducts and see if there clogged. there could be more to it also, like wiring etc. maybe someone else can shed some light? |
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| Author: | Reed [ Tue Sep 16, 2008 10:25 pm ] |
| Post subject: | |
Does the fan turn on when you move the switch? Does air come out of the ducts? Have you checked the fuses? Have you cleaned out the heater housing? Have you flushed your cooling system? |
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| Author: | stephaniebrite77 [ Tue Sep 16, 2008 10:34 pm ] |
| Post subject: | |
I had the same problem once, my blower motor had stopped working.. figured out the connector to the switch (under the dash, right near the stereo) wasn't plugged in all the way. Something else to check.. |
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| Author: | 1974duster [ Wed Sep 17, 2008 8:00 am ] |
| Post subject: | |
i use to work but now it does not i will check fuse and the wires too |
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| Author: | Reed [ Wed Sep 17, 2008 8:46 am ] |
| Post subject: | |
What do you mean when you say "i use to work but now it does not." Do you mean the fan used to blow air but now doesn't? Do you mean the fan used to turn on but now it doesn't? Do you mean it used to get hot but now it doesn't? Not to be rude, but just saying "it doesn't work" isn't specific enough to let us help you. A malfunctioning heater could be due to a large number of items: blown resistor, blown fuse, dead fan motor, detached/corroded/faulty wiring, clogged heater core, clogged heater box (leaves blown in and packing the fiberglass shell full). We need more specific input. Punctuation is nice too. |
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| Author: | imanexcellentdriver [ Tue Dec 13, 2016 8:49 am ] |
| Post subject: | |
Hey Reed, I'm reviving this old thread because my heater fan stopped blowing. There was a short time when the fan function was intermittent but now it has stopped completely. If I run power directly to the fan, it blows full power. I've checked the fuses under the dash and they're all good. I've pulled the plugs to the switches (behind the dash) and no amount of jiggling or cleaning has made a the fan turn on. So it seems like I need to replace the switch... I have NOT pulled the switches out of the dash (it seems kinda tricky and I didn't have time to figure it out--I pulled the two nuts off but nothing loosened so I assume there are more). But in your post you mentioned a "blown resistor" and I'm not sure where that would be (unless it's part of the switch)... Does my diagnosis sound correct? And how would I locate said switch besides a lucky find in a junkyard? Thanks in advance. |
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| Author: | Reed [ Tue Dec 13, 2016 9:23 am ] |
| Post subject: | |
The two usual failure points in old Mopar heater blower motor circuits are the switch and the blower motor resistor. The blower motor is a high-amp draw device but all the power is routed through the tiny spade terminals on the back of the fan switch on the dash. This design works fine for a decade or two, but eventually corrosion builds up on the terminals creating resistance which creates heat at the terminals which melts the plastic plug in the wiring harness and causes the terminals on the switch to fail. And by fail I mean melt out of the switch body or loose contact due to a deformed plug. Sometimes all you need to do is to clean the terminals and you are good to go. Other times one must replace the switch and/or the plug in the dashboard wiring harness. The second failure point is the blower motor resistor mounted on the fiberglass HVAC shell under the dash. Pull the glove box to find it. The fan speed is controlled by running the (+) feed for the blower motor through three different circuits, each with a different resistor blocking more or less current flow. All three resistors are mounted on one fibreboard plate and screwed to the fiberglass shell under the dash. These can fail and/or the plugs corrode like the fan switch. Unfortunately, unless you find a NOS supply, those blower motor resistors are no longer available for vehicles older than 84. However, I have successfully retrofitted an 84-up resistor to an 83 vehicle. It is fairly easy, you just have to match wires to the resistors on the resistor. This is fairly easy to do since each resistor is noticeably thicker or onger than the other resistors. You situation sounds like the switch has overheated and melted the plug or failed internally. I don't know what kind of car you have, but there are usually aftermarket or NOS switches floating around from various vendors. For example, Rockauto currently sells a STANDARD MOTOR PRODUCTS HS202 that fits a 74 Dart for $15.62 plus shipping. To remove the switch you usually remove the heater controls and the switch is mounted on that plate. |
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| Author: | 69a100 [ Tue Dec 13, 2016 9:29 am ] |
| Post subject: | |
The blower resister is located on or near the heater itself. It looks like a little plastic plate with a coiled up wire that goes from one end to the other. Something like this! Good Luck https://i.ytimg.com/vi/Q-i0tytSYIM/maxresdefault.jpg |
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| Author: | Reed [ Tue Dec 13, 2016 9:38 am ] |
| Post subject: | |
If you are electrically capable, it is not a bad idea to put three relays between the blower switch and the resistor. Doing so will relieve the load on the switch (making it last longer) and improve the current flow to the blower motor (making it work better). One relay for each circuit- low, medium, high. |
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| Author: | imanexcellentdriver [ Tue Dec 13, 2016 1:15 pm ] |
| Post subject: | |
Thanks for all the great info! I know where it is now, but is there a way to test the blower resistor or is it obvious when it fails? Also, Reed, is it likely that it's the low-medium-high switch or is it in the AC/Heat/Vent/Def slider since that's what activates the fan to go on? It's a 1973 Dart, btw. |
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| Author: | DusterIdiot [ Tue Dec 13, 2016 6:13 pm ] |
| Post subject: | Bypass it.... |
Quote: is there a way to test the blower resistor
The easiest way is to make a short jumper with crimp on male spades to plug into the fan plug on the one side of the resistor and the switch plug on the other... if the resistor is tanked it will run, if the switch is tanked, it won't run... don't run for more than a couple seconds this way...
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| Author: | Reed [ Tue Dec 13, 2016 8:23 pm ] |
| Post subject: | |
Uhhhh, I would have to consult a wiring diagram for a 73 Dart that I don't have. I would first inspect the low-medium-high switch. That is where I have seen the most failures. And the failures are pretty obvious. Look for melted and blackened plastic. |
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