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Post by odzking on Jun 27, 2019 14:15:26 GMT -5
Has anyone ever had this issue? Installed a new heater motor last fall. First chance I've rally had to use it since the weather has been so crappy. I was going to a cruise-in last night and had the A/C on. Everything fine until I switched the fan to high. Fan works fine but the oil pressure gauge and fuel gauge die. Didn't notice at first and though, ooh better get some gas. Then I thought, wait I just put gas in this. Not sure what made me try it but turned the fan off, gauges come back up (slowly as they should). Only seems to do it A/C mode, fine on vent, didn't really try heat. And ONLY in HIGH setting, not med or low. Switch? Something with A/C ... any ideas?
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DynoDave
CO-ADMINISTRATOR
Motown Mopar-Wizard
Posts: 11,163
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Post by DynoDave on Jun 28, 2019 12:09:12 GMT -5
Wow, I love electrical problems...NOT! Where's Nacho? * * You've already done some good detective work. 1) So A/C on, fan on other speeds aside from high, no issue, right? 2) In vent mode (no A/C compressor), fan on high, no issue, right? Only at idle, or any engine speed? If both 1 and 2 are true, it doesn't seem likely to be fan issue, because it works OK (except with the compressor). It also seems like the compressor clutch/controls would be OK, because the issue only occurs with high blower speed. Although if the fan has excessive current draw, high speed is the only position where the resistor is bypassed, so it could be allowing excessive draw that only manifests itself under that condition. I guess out of curiosity, I'd look at my blower connection and blower motor resistor. If all seems OK, I might start looking at alternator output. Do you still have an Amp guage? If so, does it normally work? If so, what does it show when this is acting up. With either excess blower current draw, or weak alternator, thinking along the lines of voltage demand from the compressor clutch and high fan speed are dropping your voltage so low, that with the limiter in the cluster, your gauges are ceasing to function. But this is just a GUESS...thinking out loud sort of thing.
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Post by odzking on Jun 28, 2019 14:15:24 GMT -5
OK, I went out to see if I could come up with more answers. 1) no issue correct 2) no issue correct Also no issue in any of the heat modes, and yes, idol, driving, any speed. So before I read this I went out to try a few things. First I tried unplugging the blower motor. and naturally with it unplugged I could hear the compressor kick on but no fan and no issue at full speed. all right, plug the blower motor back in. Make sure it is tight and HUH! Problem gone. Now here is the part I don't understand ... IF it was getting a bad connection why did all 3 speeds work and furthermore WHY is it OK now? I cleaned connection, bend the plugs a bit so they are presses together tightly and issue seems to have disappeared. I also pu a new connector on the one end, may replace both at some point but I'm going to drive it for a while and see if this happens again. The resistor if I recall is ON the heater box, correct? If that was the issue you'd think it would be opposite, no low/medium but high, fine. Ugh, I really need to rewire this car!!!!!!!!!!!!!!!!!!!!!!!!11
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DynoDave
CO-ADMINISTRATOR
Motown Mopar-Wizard
Posts: 11,163
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Post by DynoDave on Jun 28, 2019 21:16:12 GMT -5
Yes, it hangs down into the box, actually. Flat on the outside, with the male terminals sticking up. Inside, 2 coils of different lengths provide the 2 different resistances that create the slower blower speeds. High is straight battery voltage (12v) without passing through the resistor.
And why did the problem go away? I have no idea. Hopefully not a short in that high power wire, or in the control head/switch.
As notorious as it is, I wonder if that high speed fan wire feed gets it's incoming power through the bulkhead connector? Has to be coming into the car somewhere.
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Post by hanks73340 on Jun 29, 2019 5:52:14 GMT -5
What about the fuse that the new heater motor uses. Is it old and would it need to be replaced due to a stronger current coming thru the fuse? Just thinking out loud here.........
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Post by 71se3834v on Jun 29, 2019 7:01:27 GMT -5
Possibly some corrosion causing resistance for the power to flow and when you removed and replaced connection it cleaned itself allowing for more amperage to flow.
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Post by odzking on Jun 29, 2019 11:04:26 GMT -5
Possibly some corrosion causing resistance for the power to flow and when you removed and replaced connection it cleaned itself allowing for more amperage to flow. What i was thinking as well. Those connections will be replaced shortly. They are right over the exhaust manifold on passenger side ... and loose.
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bword
New Member
Posts: 3
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Gremlins
Jun 29, 2019 13:07:33 GMT -5
via mobile
Post by bword on Jun 29, 2019 13:07:33 GMT -5
I just bought a 1973 Charger with the 400 4barrel. Good car, but has a few electrical issues. Most importantly the dash/instrument lights will not work. After investigating the fuses and connections, the 5 amp fuse in slot #5 has no power when replaced and tested. The rest of the fuses work well. Any thoughts Thanks for the help Brad
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Post by Nacho-RT74 on Jun 30, 2019 8:42:25 GMT -5
I just bought a 1973 Charger with the 400 4barrel. Good car, but has a few electrical issues. Most importantly the dash/instrument lights will not work. After investigating the fuses and connections, the 5 amp fuse in slot #5 has no power when replaced and tested. The rest of the fuses work well. Any thoughts Thanks for the help Brad Welcome! Begin your own thread to ask about that
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Post by Nacho-RT74 on Jun 30, 2019 8:44:30 GMT -5
About the problem... will cehck later... I have been REALLY BUSY on these days and need to take a nap LOL.
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