1995 Mercury Cougar Heat not working at full potenial

Hello Brandon

Please check both heater hoses going into the fire wall when the car is at operating temperature. Are they both hot or is one hot one cooler?

Does your car heat up normally or is the temp gauge hotter than normal or cooler than normal?

Is the shaft loose on your water pump or is it leaking anywhere?

Why did you change the heater core, thermostat etc in the first place?

I have checked both hoses going into the heator core. Both are heating up with no problems. The hose from the radiator to the thermostate get warm as well. My car only has a resevoir tank, as from what i have inspected all the hoses seem to be ok.

If I let the car run without the heat on it warms up to normal temp. As soon as I turn the Heat on the temp gauge dropes and then fluctuates, never overheating.

I haven't noticed the water pump leaking or anything unsual.

I changed the heator core about a year and half ago. It was leaking fluid into the inside passenger side floor. After it was changed it never seemed to work the same again. I replaced the termostate and it really only seemed to make it worse. A friend of mine said to make sure it wasnt upside down and it isnt. Is there another thermostate? I know some have 2. I also have the digital climate control. Someone said if that is disconnected it needs to be reprogrammed? Have you hear of this?

The transmission went out this past year and the car sat for about 6 months being started periodically but not driven. Another thing that might help, when I turn the heat on and off you can hear the vent door close almost like a clap. It seems to be working fine though. Sorry for all the info, but nobody can seem to help me. I know a few mechanics and I have done everything they have suggested. Like I said before the only thing I havent done is change the water pump, radiator, and the thermostate again.

Also not sure if this really effects it or not, but my exhaust flanges arent 100% secure onto the manifold, one bold on each side has broken off. I tried extracting myself but cant, I have to take to a muffler shop, so that will be fixed shortley if it is the problem. Although, this was happening before exhaust wasnt secure.

Again, Thank You very much for your time on this. I can deal with the cold but I dont want my son too.

Hello –

Okay……..I am going to kind of answer/question as I read your relpy……

It sounds like when I read about the hoses going to the heater core that they get warm…but not hot. At about 190 degrees…..that should be pretty hot to touch………..and again both should be hot……..if one is hotter than the other…..then you either have blockage or air in the system.

Operating temp….heat on…fluctuate……..There is a TSB on that part……….a defective temp sender that may be this problem……….but does the temp gauge drop a lot? Was it doing that after the core change before the thermostat change?

I don’t feel your water pump is a problem……….no leaks……..the shaft is tight……..

The thermostat you put in………you car can take a 180 or 195 degree…..I would put in the 195 degree thermostat………no, only the one thermostat….but it may be too low of a temp one.

I don’t see where anything needs to be programmed….plus you said it started after the heater core change…………..so…..I just kind of wonder…..unless a cable or something wasn’t put on right or knocked out of line….but like you say later on….you can hear the doors etc……

I have attached how you check for trouble codes……….please run the test to see if you have any codes.

3. Perform the SATC System Self Test using the procedure that follows. Record all trouble codes displayed during the self test.
• The self test can be initiated at any time with any resulting trouble codes. Normal operation of the system stops when self test is activated.
• To enter self test, position the blower control knob at AUTO and the Function Selector Knob in either PANEL or FLOOR.
• Then, press the COOL and OUTSIDE TEMP buttons simultaneously and press the WARM button within two seconds. The display will show a tracer segment going in a counterclockwise direction in the center of the display window during the self test.
• When the self test is completed, Trouble Codes for any fault will be displayed in the VFD Window. If no faults are found, all display segments will illuminate.
• To exit Self Test and RETAIN all Trouble Codes, press the COOL (BLUE) button.
• To exit Self Test and CLEAR all Trouble Codes, press the OUTSIDE TEMP button and then, press the WARM button.
• After exiting the Self Test, the ignition should remain ON for at least 25 seconds to allow the temperature blend door actuator to calibrate.
• During normal operation, each intermittent trouble code will be deleted after 80 ignition switch cycles.
4. If any Trouble Codes appear during the Self Test, follow the diagnostics procedure given under "ACTlON" for each Trouble Code given. The SATC Self Test will detect faults in the system temperature and blower speed control functions found during the Self Test and will display these codes in addition to intermittent trouble codes for faults that occur during system operation. The vehicle interior temperature must be between 50°F and 90°F when performing the Self Test. If the temperatures are not within the specified ranges, false in-car temperature sensor trouble codes will be displayed.
5. If no DTCs are generated as a result of the self-diagnostic test (88°F°C code is displayed), determine the symptom(s) and go to the Symptom Chart.

Now when it sat…..what coolant did you have in it…………dex-cool or Prestone?

No, no………don’t be sorry for all the info……..the more the better my friend! Just like the sitting….that may be a clue….

The exhaust flange……….well, no, I don’t feel that would have any affect on that…..a muffler shop could fix you up pretty quick. My only concern for you there is more the exhaust gas getting inside the car…………

The other thing……..even though your car is a 1995, it appears from what I see you can use an ODB-II scanner to check other codes. Please go to Auto Zone (AZ) or O’Reilly’s (OR) and for FREE they can pull the codes to the car. Most important: Once they check your codes, if they find something and you don’t get it fixed and need to get back with us, please make sure you tell us exactly what the code was, number and all. Example, if the code was E0568 O2 Sensor bad. Then make sure you give us all of that. While there for FREE also they can bring their tester out and check your battery and alternator.

My suggestion………..

Run the test above…………on the SATC

Stop by AZ and get the car codes checked and since you are there the battery and alternator.

Check the heater hoses for hot…..or just you know……nicely warm…..

The type coolant you are using……….or it sat with……………..

Let me know what you find……….

wow...a whole lot of trouble just so I dont have to mae car payment every month huh? I have clue as to what it might be, but I will answer you questions then give my suggestions at the end.

Both Heater core hoses are hot all the way through.

The temp gauge only seems to drop when I turn the heat on. If I were to leave the heat off and drive my normal 30 mile trip to work it would heat up to normal temp.

The thermostate is a 195 degree thermostate that I got from Advance Auto. Autozone didnt carry the proper one. I am thinking I should go to the dealership and get one.

I dropped my clove box to check all wire connections and everything seemed to be fine. The problem I have is I cannot find any information, diagram, etc. on the wiring diagram or the cooling system. I have looked on the internet, in repair manuals, nothing. I did see a wiring harness that wasnt plugged into anything, but I think that used to belong to the factory amp that was in the car.

I ran the self test 88°F°C code was displayed. I heard the actuator reset.

I put prestone in it? It says Merconn. I dont think my car takes dex-cool, but im not saying im right either. It sat with prestone in it, but that coolant had only been in there for maybe 6 months. It was changed when I changed the heator core.

I didnt think the exhaust was the problem either.


I just put a new Duralast Gold batter in there cause the one died while it sat, and new alternator in there so I know those are good.

Okay......My thoughts. Could it be that the blend door actuator or bleen door itself have broken? That could explaing why when I turn my heat on the temp drops and I feel more air then heat from the vent. I think it is not closing and the wrong air mixture is making the heat and temp of my car drop. My only problem is I have not been able to locate any info pertaining to that equipment. I found a few things online, but they were for a lincoln town car. I know they are similar in a way but I dont want to rooting around in my climate system without knowing what I am doing. The other thing I thought of was maybe the actual climat control unit needed to be replaced.

Again, thank you for your time on this.

Hello - No.....I agree............the way I see it, until my maintenance cost out does a monthly car payment........I work on it :) Thanks for answering my questions.......... I agree...........I would at least change the thermostat........but look that one over really good when you remove it.......... Prestone...........good on you.........the reason I asked is we have so many different TSBs and other info about Dex-cool clogging up things.........but both your hoses are hot........... Well............I hate to say but I went all through the tech manual I have and I don't have anything other than the pic below on the system.........which is frustrating......... I agree with you in the fact that it is one or the other........but there wasn't a code thrown....the codes I see are like the below........... If it were me..........I would change the thermostat...........that should take care of the temp fluctuation unless it is the sender per the TSB I located on the temp fluxing.......... Next, if it were me I would gently go into the system and operate the controls and see it the actuators are working.............you may be able to remove the blower and reach your hand in and see if the door is closing/opening correctly.....I think the heater core is right by it first.......just a thought............. I think either way it is going to be exploratory surgery............... I wish I could provide more on the HVAC but there just isn't any pic........... Then last resort...........and please check back if you would like...........the climate control but they really didn't provide much info on this system.............. I hope this helps some...............

Temperature Gauge - Reads Low/Erratic Notes Article No. 95-13-2 07/03/95 ^ GAUGE - TEMPERATURE-READS IN LOW RANGE - ERRATIC READINGS ^ SERVICE PARTS - RETURN OF OBSOLETE TEMPERATURE SENDERS FORD: 1981-94 ESCORT 1981-95 MUSTANG, THUNDERBIRD 1983-95 CROWN VICTORIA 1984-94 TEMPO 1986-95 TAURUS LINCOLN-MERCURY: 1981-92 TOWN CAR 1981-95 COUGAR 1983-95 GRAND MARQUIS 1984-92 MARK VII 1984-94 TOPAZ 1986-95 SABLE 1987-89 TRACER 1991-94 TRACER 1993-95 MARK VIII LIGHT TRUCK: 1982-95 BRONCO 1983-95 RANGER 1986-94 AEROSTAR 1990-95 F-150-350 SERIES 1991-95 EXPLORER 1992-95 ECONOLINE 1995 WINDSTAR ISSUE: Temperature Sender F1SZ-10884-A with a build date code prior to 2774 (277th day of 1994) should be purged from your inventory and returned to your facing PDC. These parts are being made obsolete because of an incorrect crimp during assembly. Installing these parts on a vehicle could result in early loss of temperature sender function. ACTION: Remove and return the suspect parts from your dealership's inventory. The obsolete parts should be withdrawn from your inventory and returned to your facing PDC within 30 days of this TSB. NOTE : USE TSB ARTICLE 93-24-8 FOR DIAGNOSIS PROCEDURE IN DETERMINING IF LOW GAUGE READINGS COULD BE ASSOCIATED WITH A TEMPERATURE SENDER CONCERN. 1. Perform 100% sort of all stock on hand. 2. Suspect stock has a build date code prior to 2774. Usable stock will have a build date code of 2774 or later. NOTE : DATE CODES ARE LOCATED ON THE SIDE OF THE SENDER HEX. 3. Usable stock can be returned to your inventory and released for normal sales. 4. Return suspect part (F1SZ-10884-A) to your facing PDC using the least expensive transportation. 5. If claim is processed electronically via DOES II, use return code "GB"; otherwise, complete a separate paper claim form FPS-340 using return code "J". 6. In the Remarks Section, write "Returned per TSB 95-13-2". LIMITS ^ The returns must be received within 30 days from the date of this TSB. ^ Returns are restricted to the subject parts. ^ The parts returned must have been purchased from FCSD in accordance with Policy and Procedure Bulletin 4000. CREDIT Credit for parts and prepaid freight costs will be issued. Replacement stock is available for ordering PART NUMBER PART NAME F1SZ-10884-A Temperature Sender OTHER APPLICABLE ARTICLES: 93-24-8 WARRANTY STATUS: INFORMATION ONLY OASIS CODES: 203000, 203200, 204000, 204200, 402000