Cooling fans

[northeast dmc]

Hello again, I have been enjoying driving the car, my question/concern is after driving for a while the temperature creeps to around 220 or just over. It will stay in that area, depending on driving conditions. The other day when I got back from picking up pizza, as I pulled into the barn, with the temperature at or just over 220, I could hear the cooling fans coming on and off. On for maybe 10 seconds then off and then back on. Should I suspect the fans or the fan relay?? Thanks for any help.

[CFI]

Hello again, I have been enjoying driving the car, my question/concern is after driving for a while the temperature creeps to around 220 or just over. It will stay in that area, depending on driving conditions. The other day when I got back from picking up pizza, as I pulled into the barn, with the temperature at or just over 220, I could hear the cooling fans coming on and off. On for maybe 10 seconds then off and then back on. Should I suspect the fans or the fan relay?? Thanks for any help.

Was the AC on? That will cause radiator fan cycling.
220 seems high if the car is moving. Mine will only get that high if I’m sitting in traffic with the AC off. I highly recommend that at the very least you install one of Dave McKeens fan relays. It will prevent the fans from cycling so often, which is very hard on the electrical system (there is a huge jump in amps required when those fans first spin up).

[David T]

Make sure you have the uprated cooling fan circuit breaker or the fans will go on and off because the circuit breaker is cycling on and off. The temperature gauge may not be as accurate as you think. The otterstadt switch is what should be controlling the fans unless the A/C is on and cycling.

[Jonathan]

Keep in mind not all otterstats are created equal. I bought a replacement last season and realized that the on/off temperatures were not the same as the one I took out. I don't remember the specifics of what those temperatures were. They are stamped right on the otterstat though.

[LimitedRunDouglas]

Make sure you have the uprated cooling fan circuit breaker or the fans will go on and off because the circuit breaker is cycling on and off. The temperature gauge may not be as accurate as you think. The otterstadt switch is what should be controlling the fans unless the A/C is on and cycling.

Does the Delorean website sell this upgrade? Can you link it?

[David T]

Before you buy it you should check if you already have it. The vendors call it their relay and circuit breaker upgrade kit. Depending on which vendor you go to, the number of relays can vary along with the type of circuit breakers.

[Bitsyncmaster]

Before you buy it you should check if you already have it. The vendors call it their relay and circuit breaker upgrade kit. Depending on which vendor you go to, the number of relays can vary along with the type of circuit breakers.

Yes, just pull the breaker up and look if it says 40 amps. It's the breaker with only two heavy gauge wires.

One thing to note, I just had a user contact me because his 20 amp fuses are sometimes blowing on his fan fail. So his OEM fans have really gone bad. So even a 40 amp breaker may be tripping with OEM fans.

[northeast dmc]

Was the AC on? That will cause radiator fan cycling.
220 seems high if the car is moving. Mine will only get that high if I’m sitting in traffic with the AC off. I highly recommend that at the very least you install one of Dave McKeens fan relays. It will prevent the fans from cycling so often, which is very hard on the electrical system (there is a huge jump in amps required when those fans first spin up).

I did turn the A/C off just before I got home so I could make sure that wasnt in the mix. I will check the relay, I have a lot of different stuff from different sources. The temperature used to stay fairly consistent. If I dont have any luck with the relay I will try the otterstat and hotwire the pins to see if the fans stay on then. Thanks again to all the input.

[northeast dmc]

Yes, just pull the breaker up and look if it says 40 amps. It's the breaker with only two heavy gauge wires.

One thing to note, I just had a user contact me because his 20 amp fuses are sometimes blowing on his fan fail. So his OEM fans have really gone bad. So even a 40 amp breaker may be tripping with OEM fans.

Well I had an occasion to take the car out this afternoon. And as has been the case the temp got up to around 220. On the way home I drove without the A/C to see what the temp would do. When I got home the temp according to the gauge was at or real close to 220. And the fans where on then off and with different duration. I turned the a/c on and the fans would come on. I then turned the a/c off and the fans resumed that intermittent on and off. So I decided to jump the connection on the otterstat, and the fans came on and stayed as long as I could maintain the connection. I crossed the spades with a wrench wasnt putting my hand down there to pull the terminals off. When I did this the a/c clutch kicked on every time I made this connection. Not sure if it should be doing that, and what it might mean. I will make a jumper up so I can make a better connection for the next research. I am thinking the otterstat might be the culprit, or as has been mentioned possibly the temp gauge. I am going to side with the temp gauge to be cautious.

[Bitsyncmaster]

Well I had an occasion to take the car out this afternoon. And as has been the case the temp got up to around 220. On the way home I drove without the A/C to see what the temp would do. When I got home the temp according to the gauge was at or real close to 220. And the fans where on then off and with different duration. I turned the a/c on and the fans would come on. I then turned the a/c off and the fans resumed that intermittent on and off. So I decided to jump the connection on the otterstat, and the fans came on and stayed as long as I could maintain the connection. I crossed the spades with a wrench wasnt putting my hand down there to pull the terminals off. When I did this the a/c clutch kicked on every time I made this connection. Not sure if it should be doing that, and what it might mean. I will make a jumper up so I can make a better connection for the next research. I am thinking the otterstat might be the culprit, or as has been mentioned possibly the temp gauge. I am going to side with the temp gauge to be cautious.

It does point to the otterstat but I've not heard of a bad one causing intermittent operation but I guess it's possible.

[DMC-Ron]

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

[northeast dmc]

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.

[Bitsyncmaster]

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.

[northeast dmc]

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 ?

[Bitsyncmaster]

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.

[DMC-Ron]

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.

https://www.radioshack.com/search?q=1N4003
https://www.amazon.com/s?k=1n4003+diode&crid=3P21C3ZRHDM70&sprefix=1N4003%2Caps%2C219&ref=nb_sb_ss_i_1_6

Ron

[northeast dmc]

+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.

https://www.radioshack.com/search?q=1N4003
https://www.amazon.com/s?k=1n4003+diode&crid=3P21C3ZRHDM70&sprefix=1N4003%2Caps%2C219&ref=nb_sb_ss_i_1_6

Ron

Thank you for the help.

[cdrusn]

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. :race:

[CFI]

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. :race:

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.

[cdrusn]

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. :race:

[CFI]

I believe you'll find that the start up current and strain on the electrical system is much more than running the fans constantly.

That’s inaccurate. For stock fans, yes there is a big jump in amps required for fan startup, but not for the newer low power fans. Second, low power fans that almost never come on (mine) consume zero electricity for most of the miles I’ve driven. Yours, on the other hand, consume electricity constantly. Big difference.

It sounds like your car needs some work to make it more trustworthy.

[Bitsyncmaster]

That’s inaccurate. For stock fans, yes there is a big jump in amps required for fan startup, but not for the newer low power fans. Second, low power fans that almost never come on (mine) consume zero electricity for most of the miles I’ve driven. Yours, on the other hand, consume electricity constantly. Big difference.

It sounds like your car needs some work to make it more trustworthy.

Start current on OEM fans is right around 53 amps each. I think I had tested some low current fans at half that which I think were Hervey fans. If your fans are running when you start the car your adding that running current (about 25 amps OEM fans) requirement to the 150 amps needed cranking the starter.

[cdrusn]

Anyone still using a stock fan is asking for overheating problems. I can't count how many times on this forum owners have complained about running hot and now worried about blown head gaskets yet the search for the reason seems to always be the same. Check the thermostat, air in the system, not replacing boiled out coolant, otterstat not working, fans not coming on. I just wanted to take away the fan problem from the equation.

[mr_maxime]

Anyone still using a stock fan is asking for overheating problems. I can't count how many times on this forum owners have complained about running hot and now worried about blown head gaskets yet the search for the reason seems to always be the same. Check the thermostat, air in the system, not replacing boiled out coolant, otterstat not working, fans not coming on. I just wanted to take away the fan problem from the equation.

I think the otterstat is the real junk item. My car was overheating and I replaced the fans. Didnt change the problem that they didnt turn on. Was also on a rather new otterstat. I'm sure the fans can cause problems, but the otterstat seems to be the only part that you can buy new and it still be broken.