Chrysler Repair: 1990 Labaron - Weak Heat but Boils Over., coolant temp, volt ohm meter

Question
V6 3.0L Convertable. Just flushed and filled antifreeze last week. Was sitting in 20 degree weather in idle. The normally weak heater was finally working well when it started boiling over. Never seen that before in the dead of winter. Did not notice fan going on. Also, heat controls are unresponsive and allways on defrost mode. (Which you have addressed in other answers.)

Answer
Hi Mike,
I assume you used a 50/50 mixture of anti-freeze and water. When you say 'did not notice fan going on' should I assume that it did or didn't go on, or can you verify which is the case now? It either means that the fan is bad, its relay is bad, the power to the relay is absent because of a blown fusible link, or the power for the relay (from fuse 16) is blown, or that the coolant temp sensor is not accurate. Do you have a volt-ohm meter to do some checking? Let me know and I'll tell you how to test this out. In the meantime do a readout for fault codes that might be stored in the computer memory: use the ignition key, "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remains 'on' to begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to be sure of an accurate set of counts. Let me know the counts in order of appearance and we'll go from there. The temp control not having an effect could be due to the blend door cable attached to the lever not being connected to the blend door lever. The lack of control of the distribution could be due to a break or detachment in the vacuum line from the brake booster cylinder thru the fire wall to the heater mode control.
Roland

Hi Mike,
I hope everything worked out with the heater/cooling system.  Please let me know by using the 'thank/rate' tab below.
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