Re: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan
thanks guys; never heard back from Peter, and thought i'd been missing something that should have been obvious! cheers! e On 06/May/10 20:47, Craig McCluskey wrote: On Thu, 06 May 2010 18:25:28 -0700 ernest breakfield wrote: so, can anyone tell me if there really is a low-speed function (and associated resistor) on the fan on the W123 617? Yes, I can!!! (Raises and waves hand ...) The Electrical Troubleshooting Manual shows on page 127 of the 300 section shows F12 (8 Amp) in the Fuse Box (which is hot in Run or Start) powering a 0.75 BK/RD wire that goes to pin 4 (signal 86) of the Auxiliary Fan Relay, which is one side of the relay coil. The other side of the relay coil (on pin 5 -- signal 85) connects via a 0.75 BK wire to one contact of the Receiver Drier Temperature Switch (which closes at 144 deg.F., 62 deg.C). The other contact of the Receiver Drier Temperature Switch connects through a 0.75 BR wire to ground at G101. So, when the ignition switch is in Run or Start and the Receiver Drier Temperature Switch is closed, the Auxiliary Fan Relay is energized. Also on page 127, Fuse Fc (16 Amp) in the Fuse Box (which is hot at all times) powers a 2.5 RD wire that goes to pin 3 (signal 30) of the Auxiliary Fan Relay, which is the common contact of the relay. The normally open contact (signal 87 on pin 1) goes through a 2.5 BK wire to one side of the Auxiliary Fan Motor. The other side of the Auxiliary Fan Motor connects through a 2.5 BR wire to ground at G102. So, when the Auxiliary Fan Relay is closed, the Auxiliary Fan Motor is powered. The bottom line: there is only ONE speed. Craig ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan
there is not. ernest breakfield wrote: so, can anyone tell me if there really is a low-speed function (and associated resistor) on the fan on the W123 617? Peter? Bueller? anyone?;-) cheers! e -- Kaleb C. Striplin/Claremore, OK 95 E300, 94 S500, 92 500SEL, 92 300SD, 92 300E 4Matic, 91 350SDL, 91 300D, 89 560SEL, 87 300SDL x2, 85 380SE 5.0 Euro, 85 190D, 84 190D, 84 300D euro manny, 76 240D, 76 300D, http://www.okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan
On Thu, 06 May 2010 18:25:28 -0700 ernest breakfield wrote: > so, can anyone tell me if there really is a low-speed function (and > associated resistor) on the fan on the W123 617? Yes, I can!!! (Raises and waves hand ...) The Electrical Troubleshooting Manual shows on page 127 of the 300 section shows F12 (8 Amp) in the Fuse Box (which is hot in Run or Start) powering a 0.75 BK/RD wire that goes to pin 4 (signal 86) of the Auxiliary Fan Relay, which is one side of the relay coil. The other side of the relay coil (on pin 5 -- signal 85) connects via a 0.75 BK wire to one contact of the Receiver Drier Temperature Switch (which closes at 144 deg.F., 62 deg.C). The other contact of the Receiver Drier Temperature Switch connects through a 0.75 BR wire to ground at G101. So, when the ignition switch is in Run or Start and the Receiver Drier Temperature Switch is closed, the Auxiliary Fan Relay is energized. Also on page 127, Fuse Fc (16 Amp) in the Fuse Box (which is hot at all times) powers a 2.5 RD wire that goes to pin 3 (signal 30) of the Auxiliary Fan Relay, which is the common contact of the relay. The normally open contact (signal 87 on pin 1) goes through a 2.5 BK wire to one side of the Auxiliary Fan Motor. The other side of the Auxiliary Fan Motor connects through a 2.5 BR wire to ground at G102. So, when the Auxiliary Fan Relay is closed, the Auxiliary Fan Motor is powered. The bottom line: there is only ONE speed. Craig ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan
so, can anyone tell me if there really is a low-speed function (and associated resistor) on the fan on the W123 617? Peter? Bueller? anyone?;-) cheers! e On 05/May/10 13:06, ernest breakfield wrote: hi Peter! i wasn't aware there was a low speed function on the W123 fan; if there is, mine's never worked. can you tell me where i might look to find this resistor on an '85? cheers! e On 05/May/10 09:35, Peter Frederick wrote: Pull the wire off the sensor and ground it to the engine (usually on the thermostat housing on a 617). Fan must run. If not, check: Replace fan fuse (25A) and verify current at the fuse. These often corrode, assume it's bad. Check connections at the low speed resistor. Repair if corroded. Pull sensor wire at thermostat housing and ground with ignition on, fan must run. If not, verify relay operation, replace if defective. You can jump the connection at the relay socket to test fan. If you get current flow (spark, hot wire) but no fan, it's bad. Check the connection at the fan as well, they sometimes get dirty or corroded as well. You can apply voltage from a spare battery directly to the fan wires at this connection to test it as well. Peter -Original Message- From: andrew strasfogel Sent: May 5, 2010 12:21 PM To: Mercedes Discussion List Subject: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan My 1983 300TD ran hot last weekend because the auxiliary cooling fan wasn't coming on. Could someone please tell me (step by step) how to bypass the temp sensor switch in order to test whether the fan itself is defunct, or if I have a different problem? If I need a new aux. fan is there a difference in the brands? TIA, Andrew '83 and '85 W123 300Tds ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan
hi Peter! i wasn't aware there was a low speed function on the W123 fan; if there is, mine's never worked. can you tell me where i might look to find this resistor on an '85? cheers! e On 05/May/10 09:35, Peter Frederick wrote: Pull the wire off the sensor and ground it to the engine (usually on the thermostat housing on a 617). Fan must run. If not, check: Replace fan fuse (25A) and verify current at the fuse. These often corrode, assume it's bad. Check connections at the low speed resistor. Repair if corroded. Pull sensor wire at thermostat housing and ground with ignition on, fan must run. If not, verify relay operation, replace if defective. You can jump the connection at the relay socket to test fan. If you get current flow (spark, hot wire) but no fan, it's bad. Check the connection at the fan as well, they sometimes get dirty or corroded as well. You can apply voltage from a spare battery directly to the fan wires at this connection to test it as well. Peter -Original Message- From: andrew strasfogel Sent: May 5, 2010 12:21 PM To: Mercedes Discussion List Subject: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan My 1983 300TD ran hot last weekend because the auxiliary cooling fan wasn't coming on. Could someone please tell me (step by step) how to bypass the temp sensor switch in order to test whether the fan itself is defunct, or if I have a different problem? If I need a new aux. fan is there a difference in the brands? TIA, Andrew '83 and '85 W123 300Tds ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan
Pull the wire off the sensor and ground it to the engine (usually on the thermostat housing on a 617). Fan must run. If not, check: Replace fan fuse (25A) and verify current at the fuse. These often corrode, assume it's bad. Check connections at the low speed resistor. Repair if corroded. Pull sensor wire at thermostat housing and ground with ignition on, fan must run. If not, verify relay operation, replace if defective. You can jump the connection at the relay socket to test fan. If you get current flow (spark, hot wire) but no fan, it's bad. Check the connection at the fan as well, they sometimes get dirty or corroded as well. You can apply voltage from a spare battery directly to the fan wires at this connection to test it as well. Peter -Original Message- >From: andrew strasfogel >Sent: May 5, 2010 12:21 PM >To: Mercedes Discussion List >Subject: [MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan > >My 1983 300TD ran hot last weekend because the auxiliary cooling fan wasn't >coming on. Could someone please tell me (step by step) how to bypass the >temp sensor switch in order to test whether the fan itself is defunct, or if >I have a different problem? If I need a new aux. fan is there a difference >in the brands? TIA, > >Andrew >'83 and '85 W123 300Tds >___ >http://www.okiebenz.com >For new and used parts go to www.okiebenz.com >To search list archives http://www.okiebenz.com/archive/ > >To Unsubscribe or change delivery options go to: >http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
[MBZ] Testing procedure for a nonfunctioning W123 aux. cooling fan
My 1983 300TD ran hot last weekend because the auxiliary cooling fan wasn't coming on. Could someone please tell me (step by step) how to bypass the temp sensor switch in order to test whether the fan itself is defunct, or if I have a different problem? If I need a new aux. fan is there a difference in the brands? TIA, Andrew '83 and '85 W123 300Tds ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
