I read https://www.askmehelpdesk.com/heatin...use-95884.html which was very informative.

My issue is with a Carrier Weathermaster 8000 furnace and York AC. The heat works fine, the fan only works fine, I turn on the AC and the LED blinks code 34. I replace the transformer and the 5A fuse that was blown. LED is on normal. Went through the procedure of unhooking the 24V wiring from the control board and turning on the AC, then unhooking it from the contactor, the transformer or fuse didn't blow. Then I put it back to normal, and the tranformer blew only, the fuse didn't.

I was told that this means that I need a new control board if the fuse isn't blowing but the transformer is.

But if I go and put a new transformer in, then my heat and fan will work, but when going to AC it will kill the transformer - and the fuse doesn't burn like it used to.

History:
Summer 2006 away for weekend, come home, AC was left on, it's dead. Call people who installed it. They say parts aren't covered anymore so I pay them to replace a transformer, and they put in a 5A fuse instead of the 3A that was in there. They blame the electric company on power issues for the reason the transformer and fuse blew.

A month later same thing happens, this time I see it's the same code 34. So I DIY it. I find out the transformer costs only $15, they charged $75 the first time. I buy 5A fuses cause they don't sell any 3A in normal size.

May 2007, I turn on the AC and nothing. Error code 34. I replace transformer as usual. But this time the thing blows instantly, as well as fuse. I go buy 2 transormers. I replace it and go through the procedure from my second paragraph on top.

I can't see any damage on the contactor. I can't see any damage on the control board. The AC is 10-16 years old. The furnace is 4 years old.

I'm using 3A mini fuses they fit in the slot.

Any advice is appreciated before I buy a HK42FZ014.

Until you fix problem you will keep replacing transformers. Check the 2 wires going from air handler to condensing unit.Maybe an animal or weed eater cut the wires. More than likey the problem is in this area. Look around in the condensing unit at the lw voltage wires. Check the low voltage side of the contactor as well

Quote:

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Originally Posted by kerty

I read https://www.askmehelpdesk.com/heatin...use-95884.html which was very informative.

My issue is with a Carrier Weathermaster 8000 furnace and York AC. The heat works fine, the fan only works fine, I turn on the AC and the LED blinks code 34. I replace the transformer and the 5A fuse that was blown. LED is on normal. Went through the procedure of unhooking the 24V wiring from the control board and turning on the AC, then unhooking it from the contactor, the transformer or fuse didn't blow. Then I put it back to normal, and the tranformer blew only, the fuse didn't.

I was told that this means that I need a new control board if the fuse isn't blowing but the transformer is.

But if I go and put a new transformer in, then my heat and fan will work, but wen going to AC it will kill the transformer - and the fuse doesn't burn like it used to.

History:
Summer 2006 away for weekend, come home, AC was left on, it;s dead. Call people who installed it. They say parts aren't covered anymore so I pay them to replace a transformer, and they put in a 5A fuse instead of the 3A that was in there. They blame the electric company on power issues for the reason the transformer and fuse blew.

A month later same thing happens, this time I see it;s the same code 34. So I DIY it. I find out the transformer costs only $15, they charged $75 the first time. I buy 5A fuses cause they don;t sell any 3A in normal size.

May 2007, I turn on the AC and nothing. Error code 34. I replace transformer as usual. But this time the thing blows instantly, as well as fuse. I go buy 2 transormers. I replace it and go through the procedure from my second paragraph on top.

I can't see any damage on the contactor. I can't see any damage on the control board. The AC is 10-16 years old. The furnace is 4 years old.

I'm using 3A mini fuses they fit in the slot.

Any advice is appreciated before I buy a HK42FZ014.

---

Could be bad contactor coil. Or grounded secondary wire to contactor.

It sounds like you may have broken insulation on the low voltage wires running out to the outdoor unit, Does it blow the fuse if you disconnect the low voltage wires from the contactor?

Responses appreciated:

esquire1 - I checked all of these and they look clean and in excellent condition.
Popbear - if I unhook the low voltage from the AC, either:
1- from control board it self, or
2- from contactor
, the transformer doesn't blow. As soon as I connect the contactor back, the transformer blows. The fuse doesn't blow anymore at all.
hvacservicetech_07 - It doesn't blow the fuse anymore no matter what I do, it only blows the transformer.

The coil on the contactor is bad replace it and problem solved

esquire1 , just to be clear, you suggest replacing the contactor, correct. I was thinking I should measure the resistance in the two 24v wires going to the contactor, to make sure it's infinite when they are unplugged from both the contactor and the control board, just to rule out the wiring. Why do you think it's the contactor/coil?

Thanks

You said if you disconect low voltage from contactor it doesn't blow. You hook it back and it blows? Have you checked 24 v at coil on contactor? I think contactor coil is bad.

Could you explain how to check the 24v at the coil on contactor please? Would a contactor be something that is carried in a hardware sotre or only at HVAC suppliers.

Thanks

Hvac supply house. Check for 24V at the low voltage side of contactor. You will see where 220v from supply connects to contactor and the load side at top of contactor. On the bottome of contactor is the coil. Notice on the sides of the contactor you will see the spades. 2 on each side. Measure from side to side. I'm guessing this is where you said you disconnected the low voltage to test earlier

If the coil is shorted, you won't be able to measure the voltage. Instead, measure the resistance with one wire removed. I forget what a reasonable value is, but it should show something, maybe about the same as the coil of gas valve or blower relay coil. If it is 0, you have found the problem. Electrical supplies will have the contactor too.

Thanks 4 your input, I had a wood box covering the AC pipe going to the house as well as wiring, I opened it up after measuring the resistance.

Insulation gone from the 24v wires, about a 6 inch segment. Fixed it, and covered the wiring with some casing. All is well.

Score another one for the chipmonks - better then a $300+ board

Quote:

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Originally Posted by esquire1

Until you fix problem you will keep replacing transformers. Check the 2 wires going from air handler to condensing unit.Maybe an animal or weed eater cut the wires. More than likey the problem is in this area. Look around in the condensing unit at the lw voltage wires. Check the low voltage side of the contactor as well

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This was suggested many steps ago. Glad you got things going

Quote:

---

Originally Posted by kerty

I read https://www.askmehelpdesk.com/heatin...use-95884.html which was very informative.

My issue is with a Carrier Weathermaster 8000 furnace and York AC. The heat works fine, the fan only works fine, I turn on the AC and the LED blinks code 34. I replace the transformer and the 5A fuse that was blown. LED is on normal. Went through the procedure of unhooking the 24V wiring from the control board and turning on the AC, then unhooking it from the contactor, the transformer or fuse didn't blow. Then I put it back to normal, and the tranformer blew only, the fuse didn't.

I was told that this means that I need a new control board if the fuse isn't blowing but the transformer is.

But if I go and put a new transformer in, then my heat and fan will work, but wen going to AC it will kill the transformer - and the fuse doesn't burn like it used to.

History:
Summer 2006 away for weekend, come home, AC was left on, it;s dead. Call people who installed it. They say parts aren't covered anymore so I pay them to replace a transformer, and they put in a 5A fuse instead of the 3A that was in there. They blame the electric company on power issues for the reason the transformer and fuse blew.

A month later same thing happens, this time I see it;s the same code 34. So I DIY it. I find out the transformer costs only $15, they charged $75 the first time. I buy 5A fuses cause they don;t sell any 3A in normal size.

May 2007, I turn on the AC and nothing. Error code 34. I replace transformer as usual. But this time the thing blows instantly, as well as fuse. I go buy 2 transormers. I replace it and go through the procedure from my second paragraph on top.

I can't see any damage on the contactor. I can't see any damage on the control board. The AC is 10-16 years old. The furnace is 4 years old.

I'm using 3A mini fuses they fit in the slot.

Any advice is appreciated before I buy a HK42FZ014.

---

You might have to replace your breaker switch.( FUSE)

Quote:

---

Originally Posted by kerty

I read https://www.askmehelpdesk.com/heatin...use-95884.html which was very informative.

My issue is with a Carrier Weathermaster 8000 furnace and York AC. The heat works fine, the fan only works fine, I turn on the AC and the LED blinks code 34. I replace the transformer and the 5A fuse that was blown. LED is on normal. Went through the procedure of unhooking the 24V wiring from the control board and turning on the AC, then unhooking it from the contactor, the transformer or fuse didn't blow. Then I put it back to normal, and the tranformer blew only, the fuse didn't.

I was told that this means that I need a new control board if the fuse isn't blowing but the transformer is.

But if I go and put a new transformer in, then my heat and fan will work, but wen going to AC it will kill the transformer - and the fuse doesn't burn like it used to.

History:
Summer 2006 away for weekend, come home, AC was left on, it;s dead. Call people who installed it. They say parts aren't covered anymore so I pay them to replace a transformer, and they put in a 5A fuse instead of the 3A that was in there. They blame the electric company on power issues for the reason the transformer and fuse blew.

A month later same thing happens, this time I see it;s the same code 34. So I DIY it. I find out the transformer costs only $15, they charged $75 the first time. I buy 5A fuses cause they don;t sell any 3A in normal size.

May 2007, I turn on the AC and nothing. Error code 34. I replace transformer as usual. But this time the thing blows instantly, as well as fuse. I go buy 2 transormers. I replace it and go through the procedure from my second paragraph on top.

I can't see any damage on the contactor. I can't see any damage on the control board. The AC is 10-16 years old. The furnace is 4 years old.

I'm using 3A mini fuses they fit in the slot.

Any advice is appreciated before I buy a HK42FZ014.

---

Check your low voltage wire sound to me its pinch of someplace

If you don't know how to use a multi-meter, it's time to call a professional