Chrysler Repair: rear heater in voyager will not come on; interior lamps blow fuse, refrigerant hoses, amp fuse

Question
ihave a1995 grand voyager with rear heat and air the heat will not warm up. the door locks the dome lights and the warning buzzer will not work it keeps blowing the 15 amp fuse under the hood marked engine system i am not sure if they are connected    thanks for any help you can give

Answer
Hi Daniel,
I get a bit overwhelmed when I am asked to deal with three separate problems at once, so let us take these one or two at a time. On the rear heater, the first question to answer is whether or not hot coolant is being pumped to the rear HVAC unit. If you will look under the van going along the right side you will see coolant and refrigerant hoses running from just in front of the passenger door to the rear of the van just below the HVAC area. Once you have located the hoses, drive the van and determine whether the heater hoses are hot, and are they about equally hot or not so as to establish whether you are getting flow of heated water to the heater core back there or not? Let me know the result.
On the fuse blowing in the engine compartment, I suspect that is fuse #18. Can you verify that for me? It supplies voltage to all the interior lights via a relay located in the junction box under the dash. You will see 4 smaller relays in a row at the bottom of the junction box, just above the row of 12 fuses. The rightmost relay in that row is the for the interior lights. What you will need to do is try and determine in which lighting fixture you have a short circuit. Do you have a digital voltohmmeter? If so then what you will do is remove the relay and measure the  resistance between socket #87 (which is the left vertical one in the circuit board for that relay)and ground (a shiny metal surface nearby) You should find that the reading with the ohmmeter set on its lowest numberical setting is less than one ohm. Verify that please.  Then go the the right upper 36-pin black plug at the top of the junction box and measure the resistance between each of the follow pins and ground (any metal surface of the chassis which is clean and shiney): pin 6, 22, and 29, and also go to the left lower 36-pin plug and measure the resistance of pin 29. One of those four pins should have a reading of considerably less than 1 ohm (e.g. a short circuit to ground) and then we will go from there to find the light fixture that is causing the fuse to blow.
So I will await your answers. When we are done with these issues we can deal with the power door locks.
Roland