Hope you electrially inclined can help out with our 2000 Durango, the 20 amp fuse that is connected to the horn/air cond. keeps blowing, it is the fuse panel on left side of dash. I have replaced it twice, any troubleshooting suggestions are greatly appreciated, thanks!

 

Sounds like your horn has a problem. Take off the wires to it and try again to replace the fuse and try to narrow the problem down.

 

Does the slot that the fuse mounts in have a number stamped in the plastic like 1,2,....

 

Yes it does, a label is actually on the fuse box cover, it reads: 20A HORN/AC CLUTCH 1, this is the fuse that keeps blowing. The horn will work for a short time, it seems to be when the heat or air is turned on with the dial **** that the fuse then blows. Thanks for any suggestions.

 

My very small mind might think that you have a problem with the A/C clutch circuit from your description. Bad relay, intermittent short in the compressor clutch or the wiring.



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Thanks chump, I printed that schematic and will check the compressor clutch relay. Can I do this with a multimeter? and what should I look for? Big help, thanks!

 

Well, here you go! You can always swap the relay with a like relay in the PDC, just mark what relays you move.


Description and Operation
COMPRESSOR CLUTCH RELAY
The compressor clutch relay is an International Standards Organization (ISO) micro-relay. The terminal designations and functions are the same as a conventional ISO relay. However, the micro-relay terminal orientation (footprint) is different, the current capacity is lower and the relay case dimensions are smaller than those of the conventional ISO relay.
The compressor clutch relay is an electromechanical device that switches battery current to the compressor clutch coil when the Powertrain Control Module (PCM) grounds the coil side of the relay. The PCM responds to inputs from the heater-A/C mode control switch, the electronic cycling clutch switch, the low pressure cut-off switch, and the high pressure cut-off switch.
The compressor clutch relay is located in the Power Distribution Center (PDC) in the engine compartment. Refer to the PDC label for relay identification and location.
The compressor clutch relay cannot be repaired and, if faulty or damaged, it must be replaced.

RELAY TEST
The compressor clutch relay is located in the Power Distribution Center (PDC) . Refer to the PDC label for relay identification and location. Remove the relay from the PDC to perform the following tests:
1. A relay in the de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to Step 2. If not OK, replace the faulty relay.
2. Resistance between terminals 85 and 86 (electromagnet) should be 75 ±5 ohms . If OK, go to Step 3. If not OK, replace the faulty relay.
3. Connect a battery to terminals 85 and 86. There should now be continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, see Relay Circuit Test. If not OK, replace the faulty relay.

RELAY CIRCUIT TEST
1. The relay common feed terminal cavity (30) is connected to fused battery feed. There should be battery voltage at the cavity for relay terminal 30 at all times. If OK, go to Step 2. If not OK, repair the open circuit to the fuse in the PDC as required.
2. The relay normally closed terminal (87A) is not used in this application. Go to Step 3.
3. The relay normally open terminal cavity (87) is connected to the compressor clutch coil. There should be continuity between this cavity and the A/C compressor clutch relay output circuit cavity of the compressor clutch coil wire harness connector. If OK, go to Step 4. If not OK, repair the open circuit as required.
4. The relay coil battery terminal (86) is connected to the fused ignition switch output (run/start) circuit. There should be battery voltage at the cavity for relay terminal 86 with the ignition switch in the ON position. If OK, go to Step 5. If not OK, repair the open circuit to the fuse in the junction block as required.
5. The coil ground terminal cavity (85) is switched to ground through the Powertrain Control Module (PCM) . There should be continuity between this cavity and the A/C compressor clutch relay control circuit cavity of the PCM wire harness connector C (gray) at all times. If not OK, repair the open circuit as required.

Service and Repair
REMOVAL AND INSTALLATION
1. Disconnect and isolate the battery negative cable.

2. Remove the cover from the Power Distribution Center (PDC) .
3. Refer to the label on the PDC for compressor clutch relay identification and location.
4. Unplug the compressor clutch relay from the PDC.
5. Install the compressor clutch relay by aligning the relay terminals with the cavities in the PDC and pushing the relay firmly into place.
6. Install the PDC cover.
7. Connect the battery negative cable.
8. Test the relay operation.



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I just unplugged the 2 horns, put in a new fuse, ran the air conditioner. Compressor ran correct. I then cleaned the 2 horn contacts and reinstalled. So far the horn and a/c are working correctly. I'll give it a couple of days and see if the fuse lasts. Will post back results, thank you all very much, Bob.

 

Well the fuse blew again today. I was told that if a relay goes bad that it either stays open or closed. If this is so, could it be causing the fuse to blow? Thanks.

 

Replace the relay.