diff --git a/.coveragerc b/.coveragerc
index b892dd1f25d..1f1efb96e7b 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -706,7 +706,6 @@ omit =
     homeassistant/components/mjpeg/camera.py
     homeassistant/components/mjpeg/util.py
     homeassistant/components/mochad/*
-    homeassistant/components/modbus/climate.py
     homeassistant/components/modem_callerid/button.py
     homeassistant/components/modem_callerid/sensor.py
     homeassistant/components/moehlenhoff_alpha2/__init__.py
diff --git a/homeassistant/components/modbus/__init__.py b/homeassistant/components/modbus/__init__.py
index eb55066390b..41a1e37425e 100644
--- a/homeassistant/components/modbus/__init__.py
+++ b/homeassistant/components/modbus/__init__.py
@@ -336,6 +336,8 @@ def get_hub(hass: HomeAssistant, name: str) -> ModbusHub:
 
 async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
     """Set up Modbus component."""
+    if DOMAIN not in config:
+        return True
     return await async_modbus_setup(
         hass,
         config,
diff --git a/homeassistant/components/modbus/climate.py b/homeassistant/components/modbus/climate.py
index 0ecfc7b43b6..7db416cfef3 100644
--- a/homeassistant/components/modbus/climate.py
+++ b/homeassistant/components/modbus/climate.py
@@ -28,7 +28,6 @@ from . import get_hub
 from .base_platform import BaseStructPlatform
 from .const import (
     CALL_TYPE_REGISTER_HOLDING,
-    CALL_TYPE_WRITE_REGISTER,
     CALL_TYPE_WRITE_REGISTERS,
     CONF_CLIMATES,
     CONF_MAX_TEMP,
@@ -103,8 +102,6 @@ class ModbusThermostat(BaseStructPlatform, RestoreEntity, ClimateEntity):
 
     async def async_set_temperature(self, **kwargs: Any) -> None:
         """Set new target temperature."""
-        if ATTR_TEMPERATURE not in kwargs:
-            return
         target_temperature = (
             float(kwargs[ATTR_TEMPERATURE]) - self._offset
         ) / self._scale
@@ -124,20 +121,12 @@ class ModbusThermostat(BaseStructPlatform, RestoreEntity, ClimateEntity):
         ]
         registers = self._swap_registers(raw_regs)
 
-        if isinstance(registers, list):
-            result = await self._hub.async_pymodbus_call(
-                self._slave,
-                self._target_temperature_register,
-                [int(float(i)) for i in registers],
-                CALL_TYPE_WRITE_REGISTERS,
-            )
-        else:
-            result = await self._hub.async_pymodbus_call(
-                self._slave,
-                self._target_temperature_register,
-                target_temperature,
-                CALL_TYPE_WRITE_REGISTER,
-            )
+        result = await self._hub.async_pymodbus_call(
+            self._slave,
+            self._target_temperature_register,
+            [int(float(i)) for i in registers],
+            CALL_TYPE_WRITE_REGISTERS,
+        )
         self._attr_available = result is not None
         await self.async_update()
 
diff --git a/tests/components/modbus/test_climate.py b/tests/components/modbus/test_climate.py
index e453e3d4d44..54888e069ed 100644
--- a/tests/components/modbus/test_climate.py
+++ b/tests/components/modbus/test_climate.py
@@ -8,6 +8,7 @@ from homeassistant.components.modbus.const import (
     CONF_DATA_TYPE,
     CONF_LAZY_ERROR,
     CONF_TARGET_TEMP,
+    MODBUS_DOMAIN,
     DataType,
 )
 from homeassistant.const import (
@@ -16,10 +17,12 @@ from homeassistant.const import (
     CONF_NAME,
     CONF_SCAN_INTERVAL,
     CONF_SLAVE,
+    STATE_UNAVAILABLE,
 )
 from homeassistant.core import State
+from homeassistant.setup import async_setup_component
 
-from .conftest import TEST_ENTITY_NAME, ReadResult
+from .conftest import TEST_ENTITY_NAME, ReadResult, do_next_cycle
 
 ENTITY_ID = f"{CLIMATE_DOMAIN}.{TEST_ENTITY_NAME}".replace(" ", "_")
 
@@ -222,3 +225,91 @@ async def test_restore_state_climate(hass, mock_test_state, mock_modbus):
     state = hass.states.get(ENTITY_ID)
     assert state.state == HVAC_MODE_AUTO
     assert state.attributes[ATTR_TEMPERATURE] == 37
+
+
+@pytest.mark.parametrize(
+    "do_config",
+    [
+        {
+            CONF_CLIMATES: [
+                {
+                    CONF_NAME: TEST_ENTITY_NAME,
+                    CONF_TARGET_TEMP: 117,
+                    CONF_ADDRESS: 117,
+                    CONF_SLAVE: 10,
+                    CONF_LAZY_ERROR: 1,
+                }
+            ],
+        },
+    ],
+)
+@pytest.mark.parametrize(
+    "register_words,do_exception,start_expect,end_expect",
+    [
+        (
+            [0x8000],
+            True,
+            "17",
+            STATE_UNAVAILABLE,
+        ),
+    ],
+)
+async def test_lazy_error_climate(hass, mock_do_cycle, start_expect, end_expect):
+    """Run test for sensor."""
+    hass.states.async_set(ENTITY_ID, 17)
+    await hass.async_block_till_done()
+    now = mock_do_cycle
+    assert hass.states.get(ENTITY_ID).state == start_expect
+    now = await do_next_cycle(hass, now, 11)
+    assert hass.states.get(ENTITY_ID).state == start_expect
+    now = await do_next_cycle(hass, now, 11)
+    assert hass.states.get(ENTITY_ID).state == end_expect
+
+
+@pytest.mark.parametrize(
+    "do_config",
+    [
+        {
+            CONF_CLIMATES: [
+                {
+                    CONF_NAME: TEST_ENTITY_NAME,
+                    CONF_TARGET_TEMP: 117,
+                    CONF_ADDRESS: 117,
+                    CONF_SLAVE: 10,
+                }
+            ],
+        },
+    ],
+)
+@pytest.mark.parametrize(
+    "config_addon,register_words",
+    [
+        (
+            {
+                CONF_DATA_TYPE: DataType.INT16,
+            },
+            [7, 9],
+        ),
+        (
+            {
+                CONF_DATA_TYPE: DataType.INT32,
+            },
+            [7],
+        ),
+    ],
+)
+async def test_wrong_unpack_climate(hass, mock_do_cycle):
+    """Run test for sensor."""
+    assert hass.states.get(ENTITY_ID).state == STATE_UNAVAILABLE
+
+
+async def test_no_discovery_info(hass, caplog):
+    """Test setup without discovery info."""
+    assert CLIMATE_DOMAIN not in hass.config.components
+    assert await async_setup_component(
+        hass,
+        CLIMATE_DOMAIN,
+        {CLIMATE_DOMAIN: {"platform": MODBUS_DOMAIN}},
+    )
+    await hass.async_block_till_done()
+    assert CLIMATE_DOMAIN in hass.config.components