1994 Jeep Wrangler, heater problems

Throttle position sensors on 4.0 Jeeps are very touchy and erratic at best, maybe yours is failing?

Could be the heater bypass valve is stuck or the heater core is blocked.
I'd check the heater core first.You may have trapped air in the cooling system or the heater core may be partially plugged up. Engine coolant is delivered to the heater core through two heater hoses. With the engine idling at normal operating temperature, set the temperature control knob in the full hot position, the mode control switch knob in the floor heat position, and the blower motor switch knob in the highest speed position. Using a test thermometer, check the temperature of the air being discharged at the HVAC housing floor outlets.
Temperature Reference
Ambient Air Temperature 15.5° C (60° F) 21.1° C (70° F) 26.6° C (80° F) 32.2° C (90° F)
Minimum Air Temperature at Floor Outlet 52.2° C (126° F) 56.1° C (133° F) 59.4° C (139° F) 62.2° C (144° F)
If the floor outlet air temperature is too low, Both of the heater hoses should be hot to the touch. The coolant return heater hose should be slightly cooler than the coolant supply heater hose. If the return hose is much cooler than the supply hose, locate and repair the engine coolant flow obstruction in the cooling system.
OBSTRUCTED COOLANT FLOW
Possible locations or causes of obstructed coolant flow: Pinched or kinked heater hoses. Improper heater hose routing. Plugged heater hoses or supply and return ports at the cooling system connections. A plugged heater core. If proper coolant flow through the cooling system is verified, and heater outlet air temperature is still low, a mechanical problem may exist.
MECHANICAL PROBLEMS
Possible locations or causes of insufficient heat: An obstructed cowl air intake. Obstructed heater system outlets. A blend door not functioning properly.
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be adjusted with the temperature control knob on the A/C Heater control panel, the following could require service: The A/C Heater control. The blend door actuator.
The blend door. Improper engine coolant temperature

The problem is one of your coil packs is bad. Don't throw money into sensors, they are false codes. The problem is coil packs.

Since both engines have the identical timing setup it likely will not matter which year the engine was made.
If engine came with the vehicle it may have been produced late in 94 and will carry a 95 date (production date is on sticker on door) Your distributor is "locked" and timing cannot be set except that it needs to be placed in the proper position when being installed. (pointing to the #1 wire tower on the cap with the timing mark on crank pulley at tdc. Running timing changes are made by the computer using info from the crank sensor, throttle position sensor, map sensor and cam sensor (inside the distributor housing)

make sure you have power going to the sensor, no power will not work

WELL YOU NEED TO CHECK THAT THE BLENDOORS ARE WORKING BUT OPEN HOOD WHEN CAR IS WORM TO RUNING TEMP FEEL THE HEATER HOSE THEY SHOULD BE HOT IF THEY ARE ITS MOST LIKELY BLENDOOR MOTOR OR BLENDOOR BROKE. HOPE THIS HELPS

normal for an engine to start at elevated rpm and then die back as it takes a few seconds for the ECM doing it's sensor checks and idle back to the correct idle speed
check the idle rpm with an external rpm counter as most in dash units are inaccurate at rpm lower than 1000
as for the temperature
If you have a climate control module, it uses a mixture of heater and ac to maintain the temperature that you have set
so check it for operation

Make 100% sure before you go and spend more $$$ that (1) you have good coolant flow through the heater core; get engine to operating temp,then with heater fan on high and temp control on full hot carefully grasp heater in and out hoses(i use a in-fared heat gun to diagnose). They should be very close to same temp, if not, core is plugged or if equipped with a flow control valve, its not opening or there is an air lock in system.(2) If coolant flow is good, suspect the hot/cold blend door being stuck in cold position assuming you have good air flow. Its very rare for engine cooling to be ok and heater core coolant flow be bad , caused by a failed water pump! Hope this helps! Please rate me,Thanks!

you may need to add coolant to the system, If it is full check to see if there is a valve on your heater hose running from the engine to the heater core. If there is, make sure the valve is in the open position when your heater is on and the engine is up to temp. If that doesnt help try flushing the sytem, you may have a plugged heater core.

i had the same problem. i drive a 95 so im not sure if it differs from were the fuse box is. look righ above you pedals to your far left. it should be right there. also if you instruments went out it will be a 15 fuse. its a blue fuse. next my panel went out cuz of the wires on my transmission. if yor looking at your jeep at the front. the wires will be on your left. make sure they are not burned or anything. it will be right on the side of your tranny. mind got burned by the exaust so they were shorting. check that is and see if that is what is it. for a temp fix just put some electrical tap around the wires and you should be set for a wile. good luck