Hello
I'm trying to troubleshoot the blower motor on my 3.8. The blower runs (apparently well) on high speed and draws about 16 amps. On slow speed it turns so slow as to be hardly noticeable, draws around 20 amps. The resistor is brand new and measures 3.3 ohms. Do these numbers seem right or have I got a dodgy motor? I bought another resistor from SNG and that also reads 3.3 ohms.
Thanks
Myles
Heater Blower Motor
-
mystery type
- Posts: 950
- Joined: Mon Dec 21, 2009 12:46 am
- Location: lancashire
#3 Heater motor
Hi
Yes....lots of into in the link but most is aimed, it seems, at replacing the original motor. Has to be said that the original motor is not the best. It is a single speed motor that Jaguar made dual speed by adding a resistor in circuit to get a slow speed!
Your readings sound a little odd. 16 amps at fast sounds high. I would guess at around six to ten amps although the work shop manual seems to give no figures. The slow speed setting just adds a resistor in series with the motor....very crude...so it is really very unlikely that the current will rise. If correctly wired it defies ohms law.
Quick ohms law calculation says that with a 12 volt supply even if the resistor is connected direct to earth the current that flows will be 12/3.3 which is approx 3.6 amps? So your 20 amps is either an error reading the meter or suggests a wiring fault.
I would connect the motor direct to a 12 volt supply and determine the current draw while checking it spins freely. I would check your wiring to the motor. The green/blue wire connects to the resistor. The green/yellow wire connects direct to the motor. Current draw on the low setting should be less than the fast setting presuming of course you have an original motor and wiring set up.
If your slow speed is drawing 20 amps then the resistor cannot be in series with the motor...
Yes....lots of into in the link but most is aimed, it seems, at replacing the original motor. Has to be said that the original motor is not the best. It is a single speed motor that Jaguar made dual speed by adding a resistor in circuit to get a slow speed!
Your readings sound a little odd. 16 amps at fast sounds high. I would guess at around six to ten amps although the work shop manual seems to give no figures. The slow speed setting just adds a resistor in series with the motor....very crude...so it is really very unlikely that the current will rise. If correctly wired it defies ohms law.
Quick ohms law calculation says that with a 12 volt supply even if the resistor is connected direct to earth the current that flows will be 12/3.3 which is approx 3.6 amps? So your 20 amps is either an error reading the meter or suggests a wiring fault.
I would connect the motor direct to a 12 volt supply and determine the current draw while checking it spins freely. I would check your wiring to the motor. The green/blue wire connects to the resistor. The green/yellow wire connects direct to the motor. Current draw on the low setting should be less than the fast setting presuming of course you have an original motor and wiring set up.
If your slow speed is drawing 20 amps then the resistor cannot be in series with the motor...
Julian the E-type man
1962 FHC
1966 MGB....fab little car too
1962 FHC
1966 MGB....fab little car too
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