87 740 HEATER

Jan 26th, 2004, 23:00

tried this last year without much success
hope you dont mind me trying again.

problem is the heater air is barely warm .

engine temp ok.-heater valve opening fully,pipes to heater warm but not hot,
i have'nt bled the system, having owned volvos for 30 years, never needed to, unless theres something wiered with the 740,

(noticed quite a few posts on this problem, did anyone crack it?)

any ideas much appreciated
doug

Jan 26th, 2004, 23:43

If you have no heat inside the car, there are some simple procedures to follow, assuming you do not have any form of air co. First, check the thermostat. Are you sure that the neddle stays at 12 o'clock at _all_ times? If it does not, replace. Replacement is cheap and easy.

Second, bleed the system. Empty out all coolant, lift front of the car or park in slope and then open the reservoir cap, fill about a litre of coolant, then start engine and open the heater valve fully and proceed with filling. When no more bubbles appear and when the level is steady, close cap, lower car and keep the engine running until coolant is hot and check the heat.

Third, flush the heater core. Empty out all coolant, open the top and bottom heater hoses in the engine bay and attach garden hose to the top one and turn on the water at full pressure. Stop when clear water is flushing out of the bottom hose at reasonable speed.

If none of this works, your heater box is broken and you will have to take apart dash to fix the flaps and the wire controls.

George

[link:www.ttsservices.co.uk/my%20volvos.htm|http://www.ttsservices.co.uk/imm021.jpg]

'95 940 Polar LPT (B230FK/AW71; 130k)
'87 740 GLE Turbo Diesel Intercooler (D24TIC/ZF22; 210k)

Jan 27th, 2004, 22:22

thanks George - will give it a shot tomorrow, snow permitting, and update.

vjck_uk · Feb 7th, 2004, 20:01

If you just take off the highest pipe on the heater and observe the flow through it.
If the temp of the engine is ok and the flow is good then it may be the heater matrix is not sealed around the edges inside the heater body.
The only other thing it can be is the heater controls are poorly or the felt seals on the flaps are knackered or foreign bodies (leaves)jammed in them so preventing them closing properly.
A small gap can result in a massive decrease in output temp.
Vaughan

Jan 26th, 2004, 23:00	#1
douglynn Guest Location:	87 740 HEATER tried this last year without much success hope you dont mind me trying again. problem is the heater air is barely warm . engine temp ok.-heater valve opening fully,pipes to heater warm but not hot, i have'nt bled the system, having owned volvos for 30 years, never needed to, unless theres something wiered with the 740, (noticed quite a few posts on this problem, did anyone crack it?) any ideas much appreciated doug

Jan 26th, 2004, 23:43	#2
George Holmer Guest Location:	RE: 87 740 HEATER If you have no heat inside the car, there are some simple procedures to follow, assuming you do not have any form of air co. First, check the thermostat. Are you sure that the neddle stays at 12 o'clock at _all_ times? If it does not, replace. Replacement is cheap and easy. Second, bleed the system. Empty out all coolant, lift front of the car or park in slope and then open the reservoir cap, fill about a litre of coolant, then start engine and open the heater valve fully and proceed with filling. When no more bubbles appear and when the level is steady, close cap, lower car and keep the engine running until coolant is hot and check the heat. Third, flush the heater core. Empty out all coolant, open the top and bottom heater hoses in the engine bay and attach garden hose to the top one and turn on the water at full pressure. Stop when clear water is flushing out of the bottom hose at reasonable speed. If none of this works, your heater box is broken and you will have to take apart dash to fix the flaps and the wire controls. George [link:www.ttsservices.co.uk/my%20volvos.htm\|http://www.ttsservices.co.uk/imm021.jpg] '95 940 Polar LPT (B230FK/AW71; 130k) '87 740 GLE Turbo Diesel Intercooler (D24TIC/ZF22; 210k)

Jan 27th, 2004, 22:22	#3
douglynn Guest Location:	RE: 87 740 HEATER thanks George - will give it a shot tomorrow, snow permitting, and update.

Feb 7th, 2004, 20:01	#4
vjck_uk Premier member Last Online: Jul 29th, 2017 15:54 Join Date: Nov 2002 Location: southern edge of birmingham	RE: 87 740 HEATER If you just take off the highest pipe on the heater and observe the flow through it. If the temp of the engine is ok and the flow is good then it may be the heater matrix is not sealed around the edges inside the heater body. The only other thing it can be is the heater controls are poorly or the felt seals on the flaps are knackered or foreign bodies (leaves)jammed in them so preventing them closing properly. A small gap can result in a massive decrease in output temp. Vaughan

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