95 Transport No Heat

500hpgtx · 08-26-2007, 09:24 AM

Hi Transport Fans!

Our 95 Transport is blowing cool air under all heat settings. Radiator was prev. flushed, temps 195 at guage, divertor checked cycles between H/C good. Lines to heater both Hot. I believe I may only have rear AC, I do not have heat ducts in the rear except for the intake for above rear for AC. There is a heater valve at the passenger side, rear of engine, at the firewall,
next to the AC lines. Is this a vacuum operated valve that cycles closed when AC is on? I am not getting any leaks inthe cabin, and no misty loss from evap on the windshield, and cannot detect temp diff at the lines, so I do not suspect a clogged heater core...appreciate your reponse...Kev

LMP,,thankyou for your response.. I have the 3.8 motor..Apparantly the front and the rear heat
do not give heat. I would assume that I must have rear heat if that valve is present. I do beleive that all ranges work for the ducts as well, DEF, upper and lower vents, etc.

LMP · 08-27-2007, 02:50 PM

Yes the valve you described is for rear heater core only and turns OFF on a/c or vent(upper ) settings. ON mine the vacuum actuator has separated from the valve so the valve is stuck in the last position it occupied before the failure.
NOw please make clear if your problem is only with rear or front or both, and which engine you have. ON the 3.1 there is a fixture on top of manifold that has been blamed for blockage previously.

500hpgtx · 08-27-2007, 07:45 PM

Quote:

Originally Posted by 500hpgtx

Hi Transport Fans!

Our 95 Transport is blowing cool air under all heat settings. Radiator was prev. flushed, temps 195 at guage, divertor checked cycles between H/C good. Lines to heater both Hot. I believe I may only have rear AC, I do not have heat ducts in the rear except for the intake for above rear for AC. There is a heater valve at the passenger side, rear of engine, at the firewall,
next to the AC lines. Is this a vacuum operated valve that cycles closed when AC is on? I am not getting any leaks inthe cabin, and no misty loss from evap on the windshield, and cannot detect temp diff at the lines, so I do not suspect a clogged heater core...appreciate your reponse...Kev

LMP,,thankyou for your response.. I have the 3.8 motor..Apparantly the front and the rear heat
do not give heat. I would assume that I must have rear heat if that valve is present. I do beleive that all ranges work for the ducts as well, DEF, upper and lower vents, etc.

Jeffrv · 08-31-2007, 12:03 AM

Service manual suggest several things..first turn key on, leave engine off, blower on low and cycle temperature control from cold to hot and back, you should hear temp actuator moving, if not perhaps the problem is in wiring or actaitor ot linkage.
Also if hoses on both sides of heater are about the same temp, it may indicate a blockage of the heater core or hoses. It is interesting that you say both front and back heaters don'yt work, but it could be possible that that vaccuum valve ( it is a 3 position valve) is stuck in the closed position.You might want to try disconnection the heater hoses and try to flush them with and the core with a garden hose and light pressure, this assumes water pumps, theromstat coolant level etc are all ok
Good luck
Jeff

500hpgtx · 08-31-2007, 07:31 AM

Quote:

Originally Posted by Jeffrv

Service manual suggest several things..first turn key on, leave engine off, blower on low and cycle temperature control from cold to hot and back, you should hear temp actuator moving, if not perhaps the problem is in wiring or actaitor ot linkage.
Also if hoses on both sides of heater are about the same temp, it may indicate a blockage of the heater core or hoses. It is interesting that you say both front and back heaters don'yt work, but it could be possible that that vaccuum valve ( it is a 3 position valve) is stuck in the closed position.You might want to try disconnection the heater hoses and try to flush them with and the core with a garden hose and light pressure, this assumes water pumps, theromstat coolant level etc are all ok
Good luck
Jeff

Thanks Jeff much apprec. My brother pounded me about that valve. I was not certain how it is setup, In series with the front? Or flow is impeded if closed? I chedked astuator, I am skeptical about bad blender door. 150 bucks for the valve..brothersaid he had several replaced diff vehics 60-70's cars......your thoughts? KEV

Jeffrv · 09-01-2007, 10:54 AM

Kev:
That vaccuum valve controls soley coolant flow to only the rear heater and has nothing to do with the front heater operation. My comment that neihther work tends to make me look at the source, ie water pumps, coolant level, thermostat, and collapsed or blocked hoses and associated plumbing, as well as a blocked. Lower the coolant level by a few inches in the rad, and run the engine until it gets to operating temp with the rad cap off, do you see good flow from the rad tubes? If so, water pump should be ok. Try removing the heater hoses and flushing, are they clear? If all this proves ok, I would suspect you have an actuator problem. Make sure all your fuses are OK, it is electrically run.
Good Luck
Jeff

500hpgtx · 09-04-2007, 05:14 PM

Quote:

Originally Posted by Jeffrv

Kev:
That vaccuum valve controls soley coolant flow to only the rear heater and has nothing to do with the front heater operation. My comment that neihther work tends to make me look at the source, ie water pumps, coolant level, thermostat, and collapsed or blocked hoses and associated plumbing, as well as a blocked. Lower the coolant level by a few inches in the rad, and run the engine until it gets to operating temp with the rad cap off, do you see good flow from the rad tubes? If so, water pump should be ok. Try removing the heater hoses and flushing, are they clear? If all this proves ok, I would suspect you have an actuator problem. Make sure all your fuses are OK, it is electrically run.
Good Luck
Jeff

Jeff,

Had both heater cores flushed very well today...90 degree day, but heater output at front very hot now, aai can feel some heat when checking with my hand at the rear heater core. I wonder if an auxillary pump would increase effiiency during cold winter months chicago region...thanks for your help and LMP...KEV

LMP · 09-06-2007, 05:39 AM

THere was very good heat flow from the rear until my valve failed...so an auxiliary pump....if some room was found to install it...would only be there to alleviate another existing problem...HOw had you the rear core flushed? From the front hoses, both were flushed at same time with part of it...as allowed by condition of system...through the rear. I'd check for the operation of the valve when you switch the main heater from VENT to HEAT.

500hpgtx · 09-06-2007, 08:34 AM

Quote:

Originally Posted by LMP

THere was very good heat flow from the rear until my valve failed...so an auxiliary pump....if some room was found to install it...would only be there to alleviate another existing problem...HOw had you the rear core flushed? From the front hoses, both were flushed at same time with part of it...as allowed by condition of system...through the rear. I'd check for the operation of the valve when you switch the main heater from VENT to HEAT.

Louis,
Front heat very hot therm opening on gauge 195. Rear heat is zero. I will have the temp valve installed, and have them flush agin the rear core. I do not have any books on this car, and I guess that the two lines to rear are at the full right passenger area at firewall. I have to get the heat working right my son has rheumatoid arthritis. I cannot really tell if temp valve working right. Could be stuck closed and operating mechanically.
How effective is the rear heat?....anyway, I have a GM pump on my intercooler for my Grand Prix. It is very quiet, and pump rating is 6gpm. Very small, 140 bucks from intenseracing.com. Lots of fun right?

500hpgtx · 09-08-2007, 05:53 PM

Quote:

Originally Posted by 500hpgtx

Louis,
Front heat very hot therm opening on gauge 195. Rear heat is zero. I will have the temp valve installed, and have them flush agin the rear core. I do not have any books on this car, and I guess that the two lines to rear are at the full right passenger area at firewall. I have to get the heat working right my son has rheumatoid arthritis. I cannot really tell if temp valve working right. Could be stuck closed and operating mechanically.
How effective is the rear heat?....anyway, I have a GM pump on my intercooler for my Grand Prix. It is very quiet, and pump rating is 6gpm. Very small, 140 bucks from intenseracing.com. Lots of fun right?

REar Heat resolved with flushing and new valve. DExcool gummed Up?
thanks jeff and LMP...KEV

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