[keith1969]

I have voltage at the heating coils but no heat. I have 10ohms on the coils themselves. What is the ohm reading of a good heating coil please?

[denman]

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Replacement parts for Whirlpool LE7800XSW1 Residential Dryer | AppliancePartsPros.com

I have 10ohms on the coils themselves. What is the ohm reading of a good heating coil please?
10 ohms is good.

I could not find a wiring diagram for this unit.
See the attachment for a wiring diagram for a LE9500. It uses the same timer as yours so with luck it will be close to yours.

Have you opened up the control console. The wiring diagram may be in there or it may be glued to the rear panel.

I am assuming that you saw 120 volts at the heating coil when referenced to Neutral. This can be misleading as the heater requires the full 240 volts.

First check that you have 240 volts.
Try flipping the breaker off/on slowly a couple times, sometimes you can loose half the line without actually tripping the breaker.
If this does nothing, check the voltage at the plug
L1 to L2 should be 240 volts
L1 to Neutral and L2 to Neutral, both should be 120 volts.
If OK
Unplug the unit and check the wires at the terminal strip in the machine to make sure none are loose or burned out
If OK
Check the power at the terminal strip.
Be careful as 240 volts is lethal !!!

When you tested the voltage was the dryer motor running or off?

If running then you were probably seeing the L2 voltages as the centrifugal switch should close when the motor is running. The problem would then be on the left side (wiring diagram) to L1 voltage.

Unplug the unit and check the thermal cut-off (Item 3 in Section 4).
If OK then check the high limit thermostat (Item 14 in Section 4)
If OK then check the cycling thermostat (Item 8 in Section 4)
If OK then check the timer contacts BK/R. Timer must be set to mid cycle of a heating mode.
All should be 0 ohms.

Odds are that the thermal cut-off is blown. If it is you have to find out why, see below.

Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 to 12 ohms.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can cause it to run on high and the thermostats cannot regulate it so the thermal cut-off blows.

The hi-limit should have regulated the temperature so the fuse did not blow, that is why there is a new one with the thermal cut-off..
Note: That unless there is another problem in the unit the hi-limit should never have to open. It is just a safety device with the fuse being a backup safety device.

Just in case it is not a grounded element.
With all the below the high limit will also have to be replaced.
Check that the belt is OK.
Check the seals (drum etc) in the unit. The air is pulled over the heating coils, through the drum and pushed out the exhaust. So any large seal leak will pull in room air and the cycling thermostat on the blower will run the unit hot.
Check that the lint filter is not coated with fabric softener residue which greatly reduces air flow.
Check/clean your vent system.
Check/clean the blower wheel.

If all OK you may want to replace the cycling thermostat as it's contacts may not be opening (welded shut)