Jack_K
Member
- Messages
- 369
- Location
- Australia
I'll start with I would've replaced the fan by now if I could find one. I'm still searching.
Short version:
Can anyone explain this scope pattern of what I suspect is a defective condenser fan? The top trace is the battery voltage and the bottom one is the amps. It seems unusual to me that it would have the spike on every pole. I pulled the motor apart and couldn't see anything wrong except the commutator needed cleaning. I cleaned the commutator which made minimal difference.
To me this is clearly defective but I'm not sure what could cause this. I'm crazy enough to try and fix it.
Here's the pattern that both a Spal fan and a similar Mitsuba fan give:
More info / long version:
My 1986 mini has aircon which was fitted at the dealer in Japan. I thought the fan must've been weak but it seemed to operate fine and the amp readings seemed fine too. I ignored that for a while because I knew it was a pain to remove and there's not much I could do about it.
I've been trying to sort out why with the aircon on, the engine would cut out at idle when at lights and it wouldn't restart with the AC on. Every test I did turned up no cause, my engine analyser showed everything was good. I kept blaming low grade points as when I'd switch it so the points were triggering an electronic box it was fine. Eventually it was cutting out even with this fitted. I eventually decided to fit a NOS Lucas CEI distributor which uses an external module, this has a pickup cable running by the condenser fan motor. Everything seemed perfect until I'd turn on the AC and I'd get misfires galore and the tacho going crazy. It wouldn't even idle. I quickly determined that when I unplug the condenser fan, everything is fine. I switched to a totally different ignition module as the first one was temporary. At the same time I moved the pickup wiring. Now it seems fine until I'm going down the highway at almost 100km/h and around 4000rpm. The tacho starts going crazy however I don't leave it long enough to notice much of a running issue. I think it's more to do with airflow against the fan than the engine rpm but I'm not sure yet. I suspect the fan is struggling with the airflow for some reason.
I don't know if the issue with the points was related or not. Perhaps when the motor is very hot, it pulls the voltage down too much. The alternator was barely charging with the AC at idle in drive, the voltage would slowly drop. It seems more logical that it would be an EMI issue with the pickup wire. Either way, the AC low side pressure is high at idle unless I hose the condenser. revving it in neutral makes little difference to the AC performance which is a sign of a weak fan.
The fan motor is the same as some 80s Hondas but so far I haven't found a new one that's compatible. Who'd have though nobody would be making original style fan motors for an old Civic
. I'm avoiding a used one as it could have the same issue unless I got out a scope to test it.
Ultimately the question is: Is the fan definitely defective and can it be repaired.
I don't want to throw more parts at it.
Short version:
Can anyone explain this scope pattern of what I suspect is a defective condenser fan? The top trace is the battery voltage and the bottom one is the amps. It seems unusual to me that it would have the spike on every pole. I pulled the motor apart and couldn't see anything wrong except the commutator needed cleaning. I cleaned the commutator which made minimal difference.
To me this is clearly defective but I'm not sure what could cause this. I'm crazy enough to try and fix it.
Here's the pattern that both a Spal fan and a similar Mitsuba fan give:
More info / long version:
My 1986 mini has aircon which was fitted at the dealer in Japan. I thought the fan must've been weak but it seemed to operate fine and the amp readings seemed fine too. I ignored that for a while because I knew it was a pain to remove and there's not much I could do about it.
I've been trying to sort out why with the aircon on, the engine would cut out at idle when at lights and it wouldn't restart with the AC on. Every test I did turned up no cause, my engine analyser showed everything was good. I kept blaming low grade points as when I'd switch it so the points were triggering an electronic box it was fine. Eventually it was cutting out even with this fitted. I eventually decided to fit a NOS Lucas CEI distributor which uses an external module, this has a pickup cable running by the condenser fan motor. Everything seemed perfect until I'd turn on the AC and I'd get misfires galore and the tacho going crazy. It wouldn't even idle. I quickly determined that when I unplug the condenser fan, everything is fine. I switched to a totally different ignition module as the first one was temporary. At the same time I moved the pickup wiring. Now it seems fine until I'm going down the highway at almost 100km/h and around 4000rpm. The tacho starts going crazy however I don't leave it long enough to notice much of a running issue. I think it's more to do with airflow against the fan than the engine rpm but I'm not sure yet. I suspect the fan is struggling with the airflow for some reason.
I don't know if the issue with the points was related or not. Perhaps when the motor is very hot, it pulls the voltage down too much. The alternator was barely charging with the AC at idle in drive, the voltage would slowly drop. It seems more logical that it would be an EMI issue with the pickup wire. Either way, the AC low side pressure is high at idle unless I hose the condenser. revving it in neutral makes little difference to the AC performance which is a sign of a weak fan.
The fan motor is the same as some 80s Hondas but so far I haven't found a new one that's compatible. Who'd have though nobody would be making original style fan motors for an old Civic
. I'm avoiding a used one as it could have the same issue unless I got out a scope to test it.Ultimately the question is: Is the fan definitely defective and can it be repaired.
I don't want to throw more parts at it.
