If your otterstat is engaging the AC compressor clutch, you may have a shorted (or missing) diode. Normally the otterstat only switches the cooling relay coil. by itself, it should not activate the compressor. The compressor clutch adds extra load and amperage to the otterstat contacts. This could be detrimental to otterstat internals and might explain it's behavior. Refer to the schematic insert. The diode is there to prevent the otterstat from engaging the AC clutch.
This is likely not the whole issue causing the cycling, but it should be addressed.
If your otterstat is engaging the AC compressor clutch, you may have a shorted (or missing) diode. Normally the otterstat only switches the cooling relay coil. by itself, it should not activate the compressor. The compressor clutch adds extra load and amperage to the otterstat contacts. This could be detrimental to otterstat internals and might explain it's behavior. Refer to the schematic insert. The diode is there to prevent the otterstat from engaging the AC clutch.
This is likely not the whole issue causing the cycling, but it should be addressed.
Ron
I will have to check this out. An update, I faithfully check the antifreeze and the oil before I go anywhere, call me paranoid, but I went out this morning to meet up for breakfast with a couple guys from our club. I opened the air bleeder screw, and nothing was coming out, I looked at the reservoir tank and it was low. I added more antifreeze, and waited for the air to get out then closed the bleeder and made sure the tank was about half full. And on the way to the restaurant the temp held fine. On the way back it was significantly warmer and the temp still held around 200 or just under, and was steady. When I got home the fans came on and stayed on until the temp lowered slightly. I will check on the a/c clutch next time when the fans seem to be operating properly on their own. Do you have an idea where the diode might be located? Thanks again for all the help.
I will have to check this out. An update, I faithfully check the antifreeze and the oil before I go anywhere, call me paranoid, but I went out this morning to meet up for breakfast with a couple guys from our club. I opened the air bleeder screw, and nothing was coming out, I looked at the reservoir tank and it was low. I added more antifreeze, and waited for the air to get out then closed the bleeder and made sure the tank was about half full. And on the way to the restaurant the temp held fine. On the way back it was significantly warmer and the temp still held around 200 or just under, and was steady. When I got home the fans came on and stayed on until the temp lowered slightly. I will check on the a/c clutch next time when the fans seem to be operating properly on their own. Do you have an idea where the diode might be located? Thanks again for all the help.
Sounds like you got some air out of the system. The two diodes are in the large harness to the right side of the relays. What was suggested could happen but not often a diode will short, they mostly blow open. Use your meter on diode to read the forward voltage and verify the reverse direction is open.
If your otterstat is engaging the AC compressor clutch, you may have a shorted (or missing) diode. Normally the otterstat only switches the cooling relay coil. by itself, it should not activate the compressor. The compressor clutch adds extra load and amperage to the otterstat contacts. This could be detrimental to otterstat internals and might explain it's behavior. Refer to the schematic insert. The diode is there to prevent the otterstat from engaging the AC clutch.
This is likely not the whole issue causing the cycling, but it should be addressed.
Ron
Hi, well mystery some what solved, finally traced the wires for the diode and it was removed and hard wired in. Now the question is this something I can get at any parts store, and if so what is the correct diode ?
Hi, well mystery some what solved, finally traced the wires for the diode and it was removed and hard wired in. Now the question is this something I can get at any parts store, and if so what is the correct diode ?
The diode drives the relay coil so a one amp or more rated 100 volt or more. You need the high voltage because of the inductive spike from the relay coil.
The diode drives the relay coil so a one amp or more rated 100 volt or more. You need the high voltage because of the inductive spike from the relay coil.
+1
Look for 1N4002 (100 volt), 1N4003 (200 volt), or 1N4004 (400 volt). If your area still has an active Radio Shack store they might have them. Fry's as well.
+1
Look for 1N4002 (100 volt), 1N4003 (200 volt), or 1N4004 (400 volt). If your area still has an active Radio Shack store they might have them. Fry's as well.
I don't understand why we depend on the otterstat and relays to start up the fans especially during the summer months. I have my otterstat wires jumped together and the fans come on when I start the car. The thermostat will keep the coolant at temp and having the fans on all the time will keep the car from overheating (if everything else works). Doesn't cost a thing, the fans usually last forever anyway and you don't have to worry about blowing a headgasket because a sensor, relay do not work.
I don't understand why we depend on the otterstat and relays to start up the fans especially during the summer months. I have my otterstat wires jumped together and the fans come on when I start the car. The thermostat will keep the coolant at temp and having the fans on all the time will keep the car from overheating (if everything else works). Doesn't cost a thing, the fans usually last forever anyway and you don't have to worry about blowing a headgasket because a sensor, relay do not work.
You’re also putting a strain on the electrical system that is unnecessary if your cooling system works properly. Especially if you are running the stock fans. Even during the summer, if my AC is off, my car will rarely turn the fans on. I’d have to be sitting in traffic for a while before my fans will finally come on.
What I’ve done is rig a switch in the center console directly to the otterstat. That way I have complete control over the fans, or I can let the otterstat do it.
I believe you'll find that the start up current and strain on the electrical system is much more than running the fans constantly. I don't trust the sensors and relays to do their job and keep my head gasket from blowing due to overheating. Watching the temperature gage to determine it is overheating and I need to flip a switch is also trusting a notoriously inaccurate sensor and gage. By now I would hope most owners would have changed out their low cfm fans that draw huge power loads to modern low power high cfm outputs. If not then you are tempting overheating all ready.
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Originally Posted by DMC-Ron
Dave M vin 03572
