73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Interior & Equipment => Heating, Ventilation & Air Conditioning (HVAC) => Topic started by: batcomm1 on September 09, 2021, 09:42:08 AM
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I'm having an issue with no high speed but all other speeds work fine, is there a location for a high speed fuse only to check?
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What year/model truck? Does it have an inline fuse connected to the firewall junction block stud?
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84 Silverado
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84 Silverado
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Has all speeds but high, ran a 12v directly to it, got nothing, but as I said still works on all speeds but high...(https://uploads.tapatalk-cdn.com/20210909/cc3e2aae006e874f278ca067b1b12036.jpg)
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Here ya go(https://uploads.tapatalk-cdn.com/20210909/c1f636c3567b3eb2ac7dc6c0892c7827.jpg)
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Has all speeds but high, ran 12v directly to it, got nothing, but as I said still works on all speeds but high...
You ran 12v directly to what? The blower motor?
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Has all speeds but high, ran 12v directly to it, got nothing, but as I said still works on all speeds but high...
You ran 12v directly to what? The blower motor?
Correct, was a test with the switch on ....was advised to try it and was told the blower would come on high if it was good
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If the blower motor runs at low and medium speeds, the motor works. Does the blower relay "click" when you select high blower? Do you have a test light?
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Do have test lights and meters. I'll have to check for the relay "click"
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Use an incandescent test light and probe for I+ on the orange wire (Ckt 52 in the diagram, below) at the blower relay with the blower switch set to high, mode switch set to AC, and ignition switched ON.
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Have light/12v on the orange in those listed conditions
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Did the relay "click?"
- Yes - With the blower on "High," probe the red (Ckt 2, B+) and purple (Ckt 65, blower motor) wires at the blower relay. Do both illuminate the test light equally bright?
- Yes - The blower motor should be running.
- No - If both wires are dead, repair the open in the red wire between the relay and firewall junction block, or restore B+ power to the junction block, as needed. If only the purple wire is dead, replace the relay and review the topic, "Blower Motor Relay info (Keeps blowing fuses) (http://forum.73-87chevytrucks.com/smforum/index.php?topic=24383.msg203763#msg203763)".
- No - Clip the test light to the battery positive post and probe the black wire (Ckt 150, ground) at the blower relay. Does the test light illuminate?
- Yes - Replace the relay and review the topic, "Blower Motor Relay info (Keeps blowing fuses) (http://forum.73-87chevytrucks.com/smforum/index.php?topic=24383.msg203763#msg203763)".
- No - Repair the open in the relay black ground wire or the ground wire's connection to the cab sheet metal, then recheck the high blower function.
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Might be a dumb question but...am I testing these with the relay plugged in or just on the plug end off the relay
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Wires must be connected to the relay but the relay can be unbolted from the evaporator housing if that makes for easier access.
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So...I've only got power on the right side (battery side) of this...I'm assuming it has an internal fuse? If I jumper it across all works perfectly!!!(https://uploads.tapatalk-cdn.com/20210910/b11db83081812dbd55b67848976c0157.jpg)
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Or is that strictly a "junction " and needs the posts "tied" together....
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Seems you found the problem. There is no hidden internal connection between the two posts. The posts should be bussed together with an unfused jumper and tied directly to B+ via a 12-gauge red wire connected to the starter solenoid 3/8" battery cable stud and a 6" long 16-gauge fusible link located at the solenoid end of the 12-gauge wire. At this stage, you should trace and take inventory of the wires connected to the firewall junction block to determine whether someone has reconfigured and rerouted the factory wiring so that you do not inadvertently introduce wiring conflicts that might result in an electrical fire.
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Just did an LS swap into the truck so it's a good possibility that I did something...been a long process... I wantbto thank you for all you help and patience with me and my questions, now I get to start the process of integrating the 2007 ac compressor on the LS to the stock stuff on the 84 Silverado...load of fun for sure!
Again, thankbyou for all your help!
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I was told I needed to install a high pressure switch inline on the high presser side also, gotta try and figure that one out also
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There should be multiple options to accomplish that task, including custom hoses. Good luck!
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Yup that's what I'm reading on now!
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