Faulty Intercoms: Common Causes and How to Fix Them
At Servilar, we deal with faulty intercom systems in buildings and condominiums on a daily basis. From older two-wire models to modern video-enabled setups with PIN access, one thing they all have in common is that — over time — they break down.
In this article, we share the most common causes of intercom issues, what can be done to repair them, and when it’s time to stop patching things up and go for a full replacement.
1. Intercom with no sound
One of the most frequent failures is the absence of audio between the street panel and the apartment.
Most common causes:
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Loose or broken wires, especially in older buildings
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Oxidation on terminals caused by moisture or water infiltration
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Damaged microphone or speaker, either in the indoor unit or outdoor panel
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Worn-out internal components in older units
How we fix it:
We start by testing cable continuity and checking the power supply. In many cases, a simple contact cleaning or wire reconnection solves the issue. In others, the indoor unit or outdoor panel may need repair or replacement.
2. Call button not working
When someone presses the call button and nothing happens, the issue could lie in the button itself or in the circuit behind it.
Likely causes:
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Broken or jammed buttons, often due to wear or vandalism
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No power supply to the external panel
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Damaged wiring or short circuits on the call circuit
Solution:
We replace the faulty button or reconnect wiring. In some cases, if the panel is too worn or obsolete, we recommend upgrading it — and we can sometimes maintain the original appearance while updating the internals.
3. Door doesn’t unlock when button is pressed
You hear the sound, but the electric strike lock doesn't release. This is not only frustrating but also a safety issue.
Most common causes:
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No power reaching the electric lock
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Broken connection or faulty signal relay
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Electric strike failure — either worn out or underpowered
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Damaged control board
Our approach:
We start by testing the electric lock directly with an independent power source. If it works, the issue lies in the wiring or controller. If not, we replace the strike lock. When systems are too old and keep failing, we guide clients towards a more reliable replacement.
4. Failures caused by moisture or oxidation
A large number of exterior panels fail due to exposure to rain, humidity or weather conditions. Moisture infiltrates the components, causing oxidation and short circuits.
Prevention and solution:
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We use specific sealants and waterproof casings during installation
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Damaged boards are cleaned or replaced
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In recurring cases, we recommend replacing the entire outdoor unit with a waterproof, vandal-resistant model
5. An outdated system that keeps failing
When the intercom has persistent issues in multiple apartments — weak sound, static noise, unreliable buttons, and cracked cables in stairwells — it’s usually a sign the system has reached the end of its service life.
At that point, constantly repairing is no longer cost-effective — each fix is just a temporary patch.
When Is It Time to Replace the System?
From our experience as technicians, it’s time to replace the intercom system when:
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The model is so old that replacement parts are no longer available
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The wiring is damaged or outdated, making repairs risky or unreliable
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There are frequent issues in multiple apartments
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The building wants to upgrade to a more secure access system (e.g. code, card, biometrics)
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The tenants or management are tired of constant repairs
There are modern intercoms available today that are more secure, low maintenance, and aesthetically appealing, and many of them can even work with some of the existing wiring — reducing installation costs.
Repair When It’s Worth It, Replace When It’s Best
At Servilar, we always assess with full transparency: if the system can be reliably repaired, we fix it. But if it’s outdated, risky, or costly to maintain, we recommend replacing it with a modern digital intercom system.
With options like PIN codes, RFID cards and biometric access, you’ll gain peace of mind, added convenience, and long-term value.
