Mauricej41
Member
- Joined
- Apr 6, 2018
- Messages
- 10
- Points
- 56
Hi. All pipes are connected etc, yet still no heat comes in the car even when knob is turned on red. Please help
Technical No heat in Fiat Uno 1100
- Thread starter Mauricej41
- Start date
Currently reading:
Technical No heat in Fiat Uno 1100
First does engine coolant temperature reach normal, centre of gauge/ 90 degrees approx.
Then does the two heater pipes going through the bulkhead feel the same temp as coolant pipes around engine as in top and bottom hoses etc.
If yes to all that then most likely a control flap or cable on heater box not functioning correctly.
Mauricej41
Member
- Joined
- Apr 6, 2018
- Messages
- 10
- Points
- 56
Ok tell what if the pipes going through the bulkhead don't feel the same temperature as those around the engine what then?First does engine coolant temperature reach normal, centre of gauge/ 90 degrees approx.
Then does the two heater pipes going through the bulkhead feel the same temp as coolant pipes around engine as in top and bottom hoses etc.
If yes to all that then most likely a control flap or cable on heater box not functioning correctly.
When the engine is fully warmed up and the temp. gauge is in the middle, then all the water hoses should feel equally hot, almost unbearable to hold for more than 30 seconds or so.
If the water hoses to the heater where they go through the bulkhead are not that same temp. it indicates a blockage or in some cases an air lock preventing the heater from blowing hot air into the car.
Sometimes some heater hoses have a plastic bleed screw allowing air to be released if that is the problem, once clean hot water comes out the bleed screw can be carefully re tightened ( they will break if over tightened) if there is no bleed screw it can be difficult to get the air out without burning yourself as ideally it needs to be bled when engine coolant is under pressure i.e. fully warmed up.
As an experienced, but now retired motor engineer I would very carefully slacken the highest heater hose clip where it goes through the bulkhead a little, enough to allow air/water to dribble out to remove air bubbles and then re secure the hose without burning myself,
Another way is to do the same process but with a cold engine but using a coolant pressure tester pump which is much safer.
If it cures the problem but it happens again it can indicate an air leak or even a head gasket fault allowing combustion gases to seep into the coolant system where they settle at the highest point stopping water circulating through the heater system. This would obviously need repairing.
Occasionally a heater matrix (radiator) can be blocked or faulty stopping coolant flow through the heater so would need replacing (not an easy job on most cars these days).
Note all this is assuming the engine temp. is running at it's normal temp. in the middle of the gauge, around 90 degrees Centigrade.
If engine temp. is not reaching 90 Degrees Centigrade then it could be a faulty thermostat on the engine stuck open causing the problem.
Mauricej41
Member
- Joined
- Apr 6, 2018
- Messages
- 10
- Points
- 56
Wow how do I thank you man. I will try your advice and let you know ow if I came right. Tha k you again!
@Mauricej41 did you figure out the issue? As the Uno is quite old, it's quite possible you've got rust blocking the heater core. In the past I've cleaned mine out with a garden hose pipe. The hoses that go through the firewall should be able to snugly fit a hose through.
You could try running water backwards through the heater and see if that clears it. There are 2 jubilee clamps you'll have to undo (maybe get new ones if they're the special kind that need a special tool to remove). Cut 1m or so off the end of your garden hose pipe to redirect the dirty water out of your engine bay, and then insert it into the bottom hose through the firewall. Insert the hose from your tap into the top one, and get someone to very slowly open it up. You may need to switch directions a few times if the rust is clogging up the valve or core.
With mine I'm trying to remove the whole centre console with the heater core, as mine is now way too blocked.
You could try running water backwards through the heater and see if that clears it. There are 2 jubilee clamps you'll have to undo (maybe get new ones if they're the special kind that need a special tool to remove). Cut 1m or so off the end of your garden hose pipe to redirect the dirty water out of your engine bay, and then insert it into the bottom hose through the firewall. Insert the hose from your tap into the top one, and get someone to very slowly open it up. You may need to switch directions a few times if the rust is clogging up the valve or core.
With mine I'm trying to remove the whole centre console with the heater core, as mine is now way too blocked.
I have reverse flushed heater matrix/radiator on vehicles many times, safe at low pressure and as long as the outlet isn't blocked as cooling system probably on older vehicles can stand 15psi (1Bar) only and garden hose could often have 40psi or more.
I am guessing living in a warmer Country than me that antifreeze isn't used in the vehicles, this causes a problem as apart from stopping freezing it is also a anti corrosion solution which is needed in all systems with "dissimilar metals" as in most vehicles, aluminium cylinder head , cast iron block, brass, copper and steel in other parts.
Also i seem to recall that on the Uno heater unit the temperature control knob drives a cable that operates a water valve on the side of the main unit. This valve has an adjustable linkage that may have slipped, or the cable detached of the valve is broken.
I can't recall re Fiat Uno , though in the past all vehicles had water valves but nowadays the manufacturer uses the heater matrix/radiator as another way of controlling engine coolant temperature, so just using flaps to duct the heat flow.
