{"id":5848,"date":"2025-11-10T19:25:47","date_gmt":"2025-11-11T00:25:47","guid":{"rendered":"https:\/\/stock.corvair.org\/wordpress\/?p=5848"},"modified":"2025-11-24T06:56:57","modified_gmt":"2025-11-24T11:56:57","slug":"1965-69-heater-and-a-c-blower-motor-resistor-networks","status":"publish","type":"post","link":"https:\/\/stock.corvair.org\/wordpress\/2025\/11\/1965-69-heater-and-a-c-blower-motor-resistor-networks\/","title":{"rendered":"1965-69 Heater and A\/C Blower Motor Resistor Networks"},"content":{"rendered":"\n

I became interested in heater and A\/C blower motor resistor networks for late model Corvairs recently, mostly because I wanted to find one that worked well with the higher-output heater blower motor installed in one of my Corvairs. (I found that the stock resistor network produced output that was anemic, especially on the Low fan speed. The network is bypassed on High.) Corvairs with A\/C use a second blower motor, with higher output, but began sharing the resistor network with the heater blower motor beginning in 1965. (This higher-output blower motor is similar to what is available now to replace the heater blower motor.)<\/p>\n\n\n\n

Note: I use the word “network” to denote that they contain more than one resistor and they are sometimes used together. (EMs have separate resistor networks for the A\/C blower. FCs with a gasoline heater also use a resistor network.)<\/p>\n\n\n\n

I conducted some parts book research and scoured the Interwebz to purchase a few networks that might be applicable for LM Corvairs. Some electrical testing was clearly in order, following in the footsteps of Cliff Tibbits from an article in the Fall 2007 Cool Air<\/em> newsletter<\/a>. (Many thanks to my friend Chris Henkel for setting up the test configuration.) The load applied to each resistor was a replacement high-volume motor (Four Season 35383, aka PM134) with plastic fan. Also, I allowed each resistor to warm up before measuring, so that the values were relatively stable.<\/p>\n\n\n\n

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Informal testing rig. Note two meters so that volts and amps could be measured simultaneously.<\/p>\n\n\n\n

The attached screenshot below from Excel shows the testing results. Note that I tested two examples of one of the networks. <\/p>\n\n\n\n

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Below is a summary of my research. But first, two implications that jumped out at me:<\/p>\n\n\n\n